dear masood,

the effects of temperature in kcat are exactly the same as in any other chemical reaction.I suggest you to read about eyring. plots.

anyhow there is little help in freezing the substrat as the state that matters is the transition state.As these high energy states are more unlikely to be reached at low temperature,so is the reaction to proceed.

On top of that you may have denaturation at very high and VERY LOW temperatures which would screw the kinetics as stated above.

Please remember that Km canalso be modified by temperature since it also corresponds to a bunch of kinetics constant.

try reading some books on enzyme kinetics. gathered is one written by Ferscht which is very nice

Depending on the nature of enzyme temparature is having both the positive and negative effect on velocity of enzyme reactions .

Dear Ravi

Whats your mean from the nature of enzymes?

All enzymes are protein and many of those which secretory have disulfide bounds.

Also, I know Taq that extract from a thermophillus bacteria which living in hot regions and resistant to hot temperature (about 90 C).

But my question is overally and I look forward for you valuable comments abou both increase and specially decrease T effects on velocity of enzymatic reactions?

Cheers

Thanks dear Jorg for your basical comment

Whats you idea about decreasing temperature effects?

Is it true that this decrease may be decline of moleculare movement of substarte and fix them in active site?!!! Therefore the velocity maybe increse

Sincerely

dear masood,

the effects of temperature in kcat are exactly the same as in any other chemical reaction.I suggest you to read about eyring. plots.

anyhow there is little help in freezing the substrat as the state that matters is the transition state.As these high energy states are more unlikely to be reached at low temperature,so is the reaction to proceed.

On top of that you may have denaturation at very high and VERY LOW temperatures which would screw the kinetics as stated above.

Please remember that Km canalso be modified by temperature since it also corresponds to a bunch of kinetics constant.

try reading some books on enzyme kinetics. gathered is one written by Ferscht which is very nice

Dear Felipe and Jorg

Your comments are very valuable and applicable.

Thanks a lot for your kindly helps and guides.

Best Regards

Jorg Sir is their any enzymes which does not follow michalies -menten kinetics

Of course there are. Look at those who are inhibited by substrate (like pkf2 from coli) or those whose ligands bind cooperatively like the eukarioric pfk.

Depends on the enzymes involved. Of course the substrates will interact with the catalyst more often with an increased temperature, but each enzyme has an optimum functioning temperature range that is very small. Most human enzymes function optimally at body temperature. Therefore, if you are looking at velocity of reactions, it would be more advisable to pick the optimum temperature of the enzyme for the reaction and increase concentration of substrate than to increase temperature. You run the risk of denaturing your enzyme, or pushing out of its optimal functioning temperature.

Hi all scientists

Is it true that in zero degree of celesius, the rate of some enzymatic reactions increased?

This sentense is belong to one of researcher that expert in enzymology.

If is it true/false, please discusse your ideas for me.

Cheers

Dear Jorg

Is it true for all enzymes that work in aqueous solutions?

He say that in 0 C, water is being ice, therefore the concentration of substrate will incresed and also V will increased.

Whats your idea?

The rate of an enzyme-catalyzed reaction increases as the temperature is raised in most chemical reactions. The reaction rate increases with temperature to a maximum level and then abruptly declines with further increase of temperature due to enzyme denaturation. Thermal stability could be increased by enzymatic immobilization in which enzyme structure is stabilized by covalent bonds formation, i.e. via protein amino groups. The covalent bond formation might also reduce the conformational flexibility of the enzyme molecule and may lead an increase in the activation energy of the enzyme to reorganize an optimum catalytic conformation for binding to its

substrates.

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