Fang Hui（方輝）， Li Shengjie（酈圣捷）， Zhu Qiuhong（朱秋紅）， Pan Huiyun（潘慧云），and Xiao Dangsheng（肖黨生）*

The First Affiliated Hospital， Zhejiang university， Hangzhou 310000， ChinaSupproted by： Project Supported by The National Natural Science Foundation of China （81300302）*Corresponding author： Email： xds0762_cn@hotmail.com

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A novel understanding about oxidization of glucose in term of Wuxing TCM theory

Fang Hui（方輝）， Li Shengjie（酈圣捷）， Zhu Qiuhong（朱秋紅）， Pan Huiyun（潘慧云），and Xiao Dangsheng（肖黨生）*

The First Affiliated Hospital， Zhejiang university， Hangzhou 310000， China
Supproted by： Project Supported by The National Natural Science Foundation of China （81300302）
*Corresponding author： Email： xds0762_cn@hotmail.com

ABSTRACT

Yin-yang theory and Wuxing theory are the core parts of Traditional Chinese Medicine （TCM）. Most of researches on Wuxing theory are based on the paradigm of TCM or Traditional Chinese Culture. It is an evitable challenge to interpret Wuxing theory in the term of biomolecular， biochemistry， stem cell and so on. The oxidation of glucose is the important pathway in cell and there are five basic factors which will be responsible for the undergoing of this reaction. The relationships among these factors are similar to Wuxing theory just like inter-promotion and inter-restraint. So， this understanding on Wuxing theory maybe take some advancement for the modernization of TCM.

Wuxing theory； Oxidation； Metabolism； Interpromotion； Inter-restraint； System biology.

INTRODUCTION

The Yin-yang and Wuxing theory are the core parts in Traditional Chinese Medicine （TCM）. Early in 1973， introduction about the Yin-yang theory was first published in foreign journal1. In 1970s， the antagonistic effects between cyclic adenosine monophosphate（cAMP） and cyclic guanosine monophosphate（cGMP）， which regulated the behaviors of a cell， were discovered，and then some articles were published to give some interpretation on the relationship between the Yin-yang theory and these antagonistic effects2～4. Although not all of ideas in these articles can be accepted by TCM researchers， it should also be noted that west scholars begin to accept the concept of the Yin-yang for some of them presented their explanations about biologic phenomenon in the pattern of Yin-yang theory5～7.

Even so， there are still some doubts on core theories in TCM including the Yin-yang theory and the Wuxing theory8. Factually，most of current researches on the Wuxing theory （the theory of five elements） were still based on paradigm of TCM although many researchers had also pointed out that the development of system biology might take some new viewpoints for explaining the Wuxing theory. Now， a few of researchers try their best to give some novel understandings about the Wuxing theory in the term of biomolecular9. In the past， we have also presented our comprehensions about the Wuxing theory in the pattern of stem cell and the energy metabolism10～12. Disappointingly， there are still few progresses in the researching on the Wuxing theory for the contents of the Wuxing theory， which involve in the accurate definition of every element and the interpretation of the relationships among them， are much richer than that of yin-yang theory.

Now， interpretation about The Wuxing theory is facing some inevitable challenges， which are how to give reasonable explanations about the chemical or biochemical phenomena in the pattern of wuxing theory， for any behavior of a cell is composed of a series of biochemistries.

BASIC IDEAS ON THE OXIDATION OF GLUCOSE AND WUXING THEORY

The implication of the Wuxing theory

The Wuxing theory， originated in ancient China， is an interesting paradigm for explaining and analyzing all the phenomena in the world. The widely accepted definition about the Wuxing theory is following： Wu refers to five categories of things in the natural world， named as wood， fire， earth， metal and water；Xing means movement and transformation. So， Wuxing becomes a pattern for explaining the movement and transformation of these five elements as well as their interrelationships. In the Wuxing theory， every element of the five elements has its characteristics. The ancient understanding about characteristics of the five elements is based on the original properties of wood，fire， earth， metal and water in the natural world such as water moistens and flows downward， fire flames up， wood can be flexed and extended， metal can be changed in forms and earth can grow crops， etc. In order to set a framework for explaining all phenomena in the word with the Wuxing theory， the definitions ofthe five elements get extended， based on the initial abstraction for the properties of wood， fire， earth， metal and water. For example，the properties of flexing and extending， growth and development as well as free activity all pertain to the category of wood；warmth， heat， ascending and brightness all pertain to the category of fire； reception， cultivation and transformation all pertain to the category of earth； change， depuration and astringency all pertain to the category of metal； and moistening， downward movement，cold and coolness as well as closure and storage all pertain to the category of water13.

More contents in the Wuxing theory involve in the relationships among the five elements， including inter-promotion，inter-restraint， over restraint and reverse restraint. In order to interpret accurately the concept of the Wuxing， the five elements in the Wuxing theory will be listed in following way： woodTCM，fireTCM， earthTCM， mentalTCMand waterTCM.

Inter-promotion

Inter-promotion means that one thing will be responsible for promoting or generating another one in the five elements. The order of inter-promoting among the five elements follows certain rules and forms a circle， which is like this： woodTCMpromotes fireTCM， fireTCMpromotes earthTCM， earthTCMpromotes metalTCM，metalTCMpromotes waterTCMand waterTCMpromotes woodTCM.

Inter-restraint

Inter-restraint means that one thing controls and restrains another thing in the five element. The order of inter-restraint also follows certain rules and forms a circle， which is like woodTCMrestrains earthTCM， earthTCMrestrains waterTCM， waterTCMrestrains fireTCM， fireTCMrestrains metalTCM， metalTCMretrains woodTCM.

Over-restraint

Over-restraint refers to an abnormal state that the one element among the fiver elements excessively retains another one. The order of over restraint is the same as that of inter-restraint.

Reverse restraint

Reverse restraint refers to an abnormal state in which one element among the five elements reversely restrains and bullies the one which should restrain it. The order of reverse restraint is just opposite to that of inter-restraint， just like woodTCMreversely restrains metalTCM， metalTCMreversely restrains fireTCM， fireTCMreversely retrains waterTCM， waterTCMreversely retrains earthTCMand earthTCMreversely retrains woodTCM.

These interpretations are the generally accepted ideas of the Wuxing theory in recent decades. Our researches are partly in agreement with these ideas and the key difference is that Wuxing in our understanding is regarded as five processes in stead of five elements while these five elements have the typical characteristics of five processes respectively10～12. With our understanding，some phenomena can get accurately explained in the pattern of the Wuxing theory， such as the oxidation of glucose.

Five factors which are responsible for the oxidation of glucose

Glucose， the end product of photosynthesis， is an important molecule in living cells. In chloroplasts， light energy is transformed into chemical energy which will be carried by glucoses. And then these glucoses will attend many chemical reactions for synthesis of polysaccharide， fat， amino acids or be oxidized for releasing energy. Oxidation of glucose is a classic pathway. Here， a novel understanding about the Wuxing theory will be presented by using this classic pathway as an example.

The chemical reaction of glucose oxidation is following：

This is the basic pathway both in vivo and in vitro. In vivo，many proteases attend this reaction， which is different from that in vitro. Now， the question is how many factors will be responsible for the undergoing of this reaction.

The first factor is the supplement of substrates. There are two substrates in this reaction： glucose and oxygen which are the initial factors to generate the reaction. The two substrates are indifferent that glucose is regarded as reductant while oxygen is regarded as oxygenant. Without oxygen， the oxidation of glucose can be also carried out，which is called anaerobic degradation in vitro or glycolysis in vivo respectively while the products are perhaps lactic acids or alcohols （the products of glycolysis in vivo ） instead of carbon dioxide and water. On the other hand，without glucose， the reaction has no opportunity to occur.

The second factor is the releasing of end products. When the carbon dioxide and water leave the reaction system， the reaction system will be staying far away from chemical equilibrium and the oxidation of glucose will undergo without being inhibited by end products until the reaction reached the equilibrium.

The third factor is the appearance of catalyst. In vitro， the oxidation of glucose can undergo in the tense condition without catalysts and the reaction will be finished in a short time just like burning. This will never occur in vivo for the chemical condition in cell is very mild. It is the proteases that makes theoxidation of glucose in a mild condition. In the cell， the simplest pathway for oxidation of glucose is composed of glycolysis，tricarboxylic acid cycle， and electron transport while the end products of this pathway are carbon dioxide and water. If more proteases attend this pathway， the oxidation of glucose will become more complicated without any change on the direction of glucose oxidation. For example， when the proteases for synthesis and degradation of glycogen attend this pathway， glucoses can be firstly used to synthesize glycogen which will then be decomposed for oxidation.

The forth factor is the energy dissipation. This is always an ignored factor. The general idea is that a chemical reaction can be divided into two steps. The initial step is that molecular will be spited to form atoms and/or atomic groups and then these atoms as well as atomic group will be recombined into news molecules. In the initial step， energy， which is called activation energy， will be consumed while in the second step some energy will be released. In a chemical reaction， if the released energy is more than the activation energy， the reaction will be regarded as an exergonic reaction in which the chemical energy will be transformed into heat. In the normal condition， the oxidation of glucose is just an exergonic reaction for the released energy is more than the activation energy. Under the condition that the released energy is less than the activation energy， the oxidation of glucose can not undergo continuously.

Therefore， there are five basic factors for maintaining the undergoing of glucose oxidation： glucose （reductant）； oxygen（oxygenant）； appearance of catalysts or proteases； the releasing of end products； energy dissipation. Those five basic factors are similar to the Wuxing. If the initial definitions of Wuxing are ignored， the five factors can be classified into the Wuxing theory and the relationship among the five factors and Wuxing is just like the following： the releasing of end products is regarded as waterTCM； appearance of catalysts is regarded as woodTCM； energy dissipation is regarded as fireTCM； glucose （reductant） is regarded as earthTCM； oxygen （oxidizing agent） is regarded as metalTCM. Here， it should be pointed out that catalysts or proteases for oxidation of glucose are not necessary for oxidation of glucose in natural condition and the amount of them can also be regarded as zero in this condition.

The inter-promotion among the five factors

New classification about the five factors in the oxidation of glucose will give some novel interpretations on the Wuxing theory. In all， the inter-promotion among the five factors discovers their roles in whole process of the glucose oxidation.

EarthTCMpromotes metalTCM. This indicates the relationship between the glucose and oxygen， that the appearance of glucose will promote the oxidative function of oxygen.

MetalTCMpromotes waterTCM. This indicates the relationship between the oxygen and end products， that is the appearance of oxygen will be responsible for producing the end products （carbon dioxide and water）.

WaterTCMpromotes woodTCM. This indicates the relationship between the end products and catalyst. It is well known that the releasing of end products will help the catalyst regain their activity. The accumulation of end products will inhabit the reaction by staying the active center of the catalysts which will block the formation of catalyst-substrata complex so that catalysts can not catalyze the substrates into end products continuously and the reaction will reach the chemical equilibrium.

WoodTCMpromotes fireTCM. This indicates the relationship between the catalysts and energy. Catalysts will promote the releasing of energy when they play their function.

FireTCMpromotes the earthTCM. This indicates the relationship between the energy and glucose. The initial step of glucose oxidation is to activate the substrate which is an energyconsuming process. Under the condition that the released energy is more than the activation energy， the oxidation of glucose will undergo continuously or the reaction will get the termination.

Inter-restraint among the five factors

Inter-restraint among the five factors in glucose oxidation will take some inhabitation to the oxidation of glucose.

EarthTCMretrains waterTCM. This indicates the relationship between glucose and end-product. Glucose， a water soluble substrate， can adsorb the water （one of end product ） so as to prevent the releasing of end product， which will take some inhibition to the reaction.

WaterTCMretrains the fireTCM. This indicates the relationship between the end products and energy. It is always ignored who will take the energy released in the reaction out of the reaction system. In the exoenergic reaction， chemical reaction will be released as heat energy. Heat energy is regarded as the irregular molecular motion while energy， that a molecule is carrying，can be calculated according to the formula （E=1/2MV2）. Theoretically， this formula shows that a molecule with higher velocity will carry more energy although its molecular weight is small. The laws of collision and inertia in physics also discover that a molecule with the small molecular weight will be mucheasier to get high velocity. These physical principles imply that in the reaction system of glucose oxidation， water is the just end product to get the highest velocity so as to take the energy away. This theoretical conclusion will bring many novel viewpoints on the biological phenomena.

FireTCMretrains the metalTCM. This indicates the relationship between energy and oxygen. In the reaction， the molecular weight of oxygen is 32， much higher than that of water and less than that of carbon dioxide. This implies that energy can also be carried more easily by increasing the velocity of oxygen so as to force the oxygen leaving the reaction system. With the decreasing of oxygen， the reaction will be inhibited.

MetalTCMretrains woodTCM. This indicates the relationship between oxygen and catalyst. Catalyst is a substance which can initiate or accelerate a chemical reaction without itself being affected. In the reaction system， catalysts can also be oxidized to lose its activity， which is called catalyst poisoning. This chemical phenomenon is the relationship between oxygen and catalyst.

WoodTCMretrains earthTCM. This indicates the relationship between catalyst and glucose. During the reaction， catalyst will reduce the activity energy by the formation of catalyst-substrate complex. This complex can not only promote the reaction by reducing activity energy but also prevent the reaction by blocking the direct collision between glucose and oxygen.

THE WHOLE PROCESS OF GULCOSE OXIDATION

Because the content of the Wuxing theory is so complicated，few researchers discuss this theory in the pattern of biochemistry and/or molecular biology. Sun Lei et al. presented their understanding on the Wuxing theory in the term of biomolecules with the ignorance of original and extended definition of the Wuxing， which will bring some novel insights into the basic theory ofTCM9. Some researchers suggested that atmosphere should be regarded as metalTCMwhich has some similarity with our understanding that oxygen are classified in metalTCM14. In the past， we had published our discussion on the Wuxing theory in the term of energy metabolism and stem cell10～12. In our research，energy metabolism is the key point to interpreting the Wuxing theory. The oxidation of glucose is an exoenergic reaction while the inter-promoting and/or inter-retraining of the five factors will be responsible for the undergoing of this reaction which can be interpreted according to the Wuxing theory.

The whole process of glucose can be described in the frame of the Wuxing theory. The supplement of glucose is the initial step of oxidation and then protease and glucose form the proteaseglucose complex which should be regarded as woodTCMretrains earthTCM. The next two steps are that protease-glucose complex will be oxidized and the chemical energy will be released as heat， which should be regarded as metalTCMretrains woodTCMand fireTCMretrains the metalTCMrespectively. At last， end products will be released by carrying energy which is regarded as waterTCMretrains fireTCM. When the end products are released， a cycle of glucose oxidation process will come to the end.

During the whole process of glucose， the leading role of every factor will get changed. For example， at the initial step of oxidation， glucose plays the leading role. In the formation of protease-glucose complex， the protease plays the leading role. And then， the oxidation will play the leading role. Next， energy will play the leading role. At last， the factor that plays leading role is end products.

When one factor plays its leading role， it should also be noticed that other factors must be playing their assistant roles to support the undergoing of the reaction. For example， during the formation of protease-glucose complex， although the protease plays its leading role， glucose， oxygen， energy as well as end product will also afford their assistant for the process of glucose affording substrate， oxygen determining the fate of the complex， energy inactivating glucose and protease as well as the releasing of end products promoting the reaction.

In all， there is a successive sequence for five factors playing its leading roles during the oxidation of glucose in the pattern of the Wuxing theory， which can be concluded according to interpromoting and inter-retraining of Wuxing.

THE TERMINATION OF GLUCOSE OXIDATION

It is impossible for glucose oxidation to undergo endlessly both in vivo and in vitro. The five factors to maintain the reaction are also the factors to terminate the oxidation or to help the reaction reach the chemical equilibrium.

Glucose. Without substrates， any chemical reaction will not be carried out. So， deficiency of glucose will lead the oxidation to reach the termination. Over supplement of glucose will exhaust the oxygen so that the oxidation will get slow and even reach the termination as well.

Oxygen. In the biosphere， the deficiency of oxygen rarely occurs. Over supplement of oxygen， glucose will be oxidized as quickly as possible just like burning. Without oxygen， glucose can also be decomposed， which is called anaerobic degradationwith many middle products. In vivo， this anaerobic degradation is called glycolysis with the lactic acid or alcohol as the products.

Protease. Although protease promotes the glucose oxidation by reducing activity energy， over supplement of proteases will also inhibit the oxidation by reducing the probability of collision between the glucose and the oxygen. In vitro， without catalyst or protease， the oxidation of glucose will undergo much slowly or tensely. In vivo， without protease， the oxidation of glucose will never occur in a mild condition or the reaction will reach the termination.

Energy. Although the oxidation of glucose is an exoenergic reaction， the reaction can not be carried out unless the releasing energy is much more than activity energy or is used to inactivate the substrate. In the case that too much energy enters the reaction system， not only the oxidation of glucose can be inhibited but also the reverse reaction of oxidation （synthesis of glucose with carbon dioxide and water） will occur， just like the photosynthesis in chloroplast.

The releasing of the end products. The releasing of end products will promote the undergoing of reaction， which is the basic principle of chemistry. So， the accumulation of end products will help the reaction reach the chemical equilibrium which is the end point of reaction.

PERSPECTIVE

System biology perhaps is one of direction for the modernization ofTCM15. Currently， there are two principle streams within systems biology： 1） Pragmatic system biology， which emphasized the utilization of large-scale molecular analysis and computer technology16，17； and 2） Theoretic system biology，which will take radical changes for theoretic and methodological approaches in biological researches18. Although there are some progresses in systems biology， no general principles and practicing approaches of systems biology have been launched. Modernization ofTCM， which will bring benefits for the development of system biology， will be also helpful to set up some basic principles for system biology. In order to reach these destinations， novel interpretation on the Yin-yang and Wuxing theory as well as a new cellular model should be launched in the term of traditional biology， cytology， biochemistry and so on.

Metabolism is the fundament process in cell while the oxidation of glucose is an important part in the metabolism. In vivo， the oxidation of glucose is more sophisticated for a range of proteases attend this process. The five factors， which maintain the reaction of glucose oxidation， are also indispensable in vivo while the cell only affords the limited spaces. Factually， every factor has its pathway in living cells. These pathways can also be classified into Wuxing by their roles in the oxidation. The classification is following： the pathway for the supplement of glucose should be regarded as earthTCM； the pathway for the supplement of oxygen should be regarded as metalTCM； the pathway for the synthesis and renewal of proteases should be regarded as woodTCM； the pathway for the utilization of energy should be regarded as fire；the pathway for releasing of end product should be regarded as waterTCM. Under certain condition， one pathway will play the leading role while other pathways will play the assistant roles for the undergoing of oxidation in living cells.

In vivo， not only glucose but also fatty acid and amino acid can be oxidized and their pathways of oxidation are similar to that of glucose. So， the pathway for supplement of fatty acid and amino acid should be also classified as earthTCM. Now， if the metabolism of energy substance is regarded as the core pathway， a novel viewpoint should be accepted that cell only affords a limited space for the oxidation of these substances. In cell， the pathways are so complicated just like a network and interaction of these pathways make us nebulous. If all pathways are classified according to the Wuxing theory， it should be found that all pathways must follow the principles of Wuxing theory. Still， the relationships of Wuxing in cells are more complicated than that in vitro. For example， the concept of woodTCMretraining earthTCM，which means the formation of catalyst-glucose complex in vivo，includes the synthesis of proteins and/or proteases. Another example is that the concept of metalTCMretraining woodTCM，which means the oxidation of catalyst-glucose complex in vivo，can also be explained as decomposition of protein.

Finally， death is the evitable fate for cells. The five factors for the oxidation of glucose are the factors to keep cell in stability. The changes of these factors will take the alternation of cell in structure or/and function and extreme abnormality of any factors，and will finally lead to the death of cells. These ideas will be discussed later.

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