Helx Hellx A Fe Fe 13-00t85 N N 85-O013 Fe Fe Oxygen molecule Helbx Helbx A Helbx Helk A Fe Fe (a) Structure of deoxy protein. (b) Detail of the oxygen-binding N and C denote N-termini site in the oxy form. and C-termini. The dyad axis (d) is perpendicular to this page.
Enzyme kinetics
In biochemistry, enzymes are proteins that act as biological catalysts. Catalysis is the addition of a catalyst to a chemical reaction to speed up the pace of the reaction. Catalysis can be categorized as either homogeneous or heterogeneous, depending on whether the catalysts are distributed in the same phase as that of the reactants. Enzymes are an essential part of the cell because, without them, many organic processes would slow down and thus will affect the processes that are important for cell survival and sustenance.
Regulation of Enzymes
A substance that acts as a catalyst to regulate the reaction rate in the living organism's metabolic pathways without itself getting altered is an enzyme. Most of the biological reactions and metabolic pathways in the living systems are carried out by enzymes. They are specific for their works and work in particular conditions. It maintains the best possible rate of reaction in the most stable state. The enzymes have distinct properties as they can proceed with the reaction in any direction, their particular binding sites, pH specificity, temperature specificity required in very few amounts.
Assume that a new oxygen transport protein has been discovered in certain
invertebrate animals. X-ray diffraction of the deoxy protein reveals that it
has the dimeric structure shown in panel (a) of the accompanying figure,
with a salt bridge between residues histidine 13 and aspartic acid 85. The
two monomers interact by salt bridges between the C- and N-termini. The
O2-binding site lies between the two iron atoms shown, which are rigidly
linked to helices A and C (see panel (b)). In the deoxy form, the space
between the iron atoms is too small to hold O2, and so the Fe atoms must be forced apart when O2 is bound.
Answer the following questions, explaining your answer in each case in
terms of the structure shown below.
(a) Is this molecule likely to show cooperative oxygen binding?
(b) Is this molecule likely to exhibit a Bohr effect?
(c) Predict the likely effect of a mutation that replaced aspartic acid 85 by
a lysine residue.
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