Pedro Mendes wrote:
What we decide to call a "pathway" is in fact a completely arbitrary <
decision. Where does it start and where does it end? This is a subject <
that has been discussed several times in the past with too many good <
heads defending their own criterion of choice. In the end, all these <
criteria are arbitrary, showing that metabolism has to be seen as a <
whole (though MCA shows exactly how one can integrate the information <
about the isolated parts to the behaviour of the whole). <
There is additional help from MCA: if you measure the control <
coefficients of only a few enzymes, you will know how much of the <
total control is accounted by those enzymes by adding their control <
coefficients and comparing it with the summation theorems. For example <
you can find that after measuring the flux-control coefficients of 4 <
enzymes, their sum is 0.9; as a consequence the total control of the <
rest of the metabolism is only 0.1 in that steady state. This is <
indeed very important information! <
Using the words of the great Henrik Kacser: <
"But one thing is certain: to understand the whole, you must look at <
the whole" <
My e-mail system is damaged again so a few of my messages disappeared.
However I am glad this happened - some of them were too critical to MCA
and now I see that this was just a result of my incompetence. Although I
still know almost nothing about MCA, I feel that this is a correct and
promising approach. I will get active in it as soon as I find relevant
literature.
Pentcho
