about enzyme - hexokinase ... 急 ... help me >

Hexokinase is the enzyme that in charge of the first reaction of the glycolytic pathway, it can be regulated by the ATP level, tempeture, and pH. it Adds a Phosphate group at the Carbon-6 of the glucose molecule and produce glucose 6-phosphate.
pH changes would affect all proteins structually and charge.differet protein has different propertise of the active site, some proteins have negative charged sites, which if high level of Hydrogen ions (low pH)is presence, they would basically block/change(the shape of) the active site by netralising the charge on the protein, vice versa. also in extreme cases, like exceeding the normal physiological pH, the protein would change shape (denature) due to the enviorment, also includes tempeture.

the physiological limit is depent on the pKa of the protein. pKa is the measure of how would molecules would be charged in a enviorment.

2008-10-14 09:57:15 補充：
if u need more info, you may need to research yourself, these are the basic term u may need

The pH of a solution can have several effects of the structure and activity of enzymes.


Changes in pH may not only affect the shape of an enzyme but it may also change the charge properties of the substrate so that either the substrate connot bind to the active site or it cannot undergo catalysis.