[bryanh]

Hi
I am interested in knowing about the ways prokaryotes maximise the conversion of one reactant to another in metabolic systems. In any given pathway, a given molecule will be converted to the next in the cycle, what I want to know is can/does this conversion go wrong?

Presumablythe pre-cursor can decompose, react in other ways etc before the appropriate enzyme binds it (actually do the molecules spend much time in free solution or are they passed between enzymes pretty quickly?). Anyone know what the efficiency of the conversion to the next stage in the cycle. I would presume it would be near 100% due to the optimum conditions in the cell and effective enzymes, any thoughts on how the cell (particularly prokaryotic) maximises the conversion.

In explanation i am interested in comparing hypothetical prebiotic metabolic pathways with extant ones.

[Equi]

Hi
I am interested in knowing about the ways prokaryotes maximise the conversion of one reactant to another in metabolic systems. In any given pathway, a given molecule will be converted to the next in the cycle, what I want to know is can/does this conversion go wrong?

Presumablythe pre-cursor can decompose, react in other ways etc before the appropriate enzyme binds it (actually do the molecules spend much time in free solution or are they passed between enzymes pretty quickly?). Anyone know what the efficiency of the conversion to the next stage in the cycle. I would presume it would be near 100% due to the optimum conditions in the cell and effective enzymes, any thoughts on how the cell (particularly prokaryotic) maximises the conversion.

In explanation i am interested in comparing hypothetical prebiotic metabolic pathways with extant ones.

Hi Bryanh,

Firstly, all chemical reactions have a certain equilibrium, which cannot be altered by enzymes. Hence, one cannot talk about efficiency of conversions (which refers to the %age), but about speed and control. Usually (always), the reactions are in a steady state equilibrium exhibiting constant flow of aducts and products.

Secondly, prokaryotes either have micro-environments in their cytosol or multi-enzyme complexes. Even though the viscosity of the cytoplasm is very high, diffusion takes place quickly.

Thirdly, I hope I didn't miss your topic/question, because I'm not really sure about what you mean.

ciao,
Equi

[bryanh]

Hi, thanks for the repy
Sorry if my question was a little vague, got a cold at the moment i'm having trouble getting my thoughts out through the snot.
Your comments helped but what i am geting at is for when a particular molecule is produced in a metabolic cycle can it be in any way wasted or lost to the system? Through, for example oxidation, free radical attack, hydrolysis etc.  And how do prokaryotes minimise/prevent this waste? I'm only looking for some vague thoughts on the matter, nothing too specific but i am particularly interested in the RCC and Acetyl CoA pathways.

The answer may simply be that the molecules are all very stable in the physiological conditions of the cell.

[Equi]

Hi, thanks for the repy
Sorry if my question was a little vague, got a cold at the moment i'm having trouble getting my thoughts out through the snot.
Your comments helped but what i am geting at is for when a particular molecule is produced in a metabolic cycle can it be in any way wasted or lost to the system? Through, for example oxidation, free radical attack, hydrolysis etc.  And how do prokaryotes minimise/prevent this waste? I'm only looking for some vague thoughts on the matter, nothing too specific but i am particularly interested in the RCC and Acetyl CoA pathways.

The answer may simply be that the molecules are all very stable in the physiological conditions of the cell.

Metabolites "getting lost" only happens at the end of a pathway (i.e. waste products), to preserve efficiency intermediates are usally charged and therefore cannot diffuse through membranes (would be quite annoying if glycolysis intermediates simply leak out of the cell). Radicals occur frequently, either due to environmental sources (ionizing radiation, chemicals) or produced by the cell itself (for instance: oxidative phosphorylation steadly leads to incomplete oxygen reduction). To avoid damage by these oxygen-species cells have evolved serveral enzymes (e.g. SOD, catalase, ...) and/or they live at oxygen free conditions. In eukaryotic cells these mechanisms are even more complex (peroxysomes, etc.).

I hope that's general enough
Get well soon.