The turnover number is defined as the maximum number of substrate molecules that can be converted into product molecules per unit time by an enzyme molecule. The concentration of enzyme active sites is not necessarily equal to the concentration of enzyme molecules, because some enzyme molecules have more than one active site. If the enzyme molecule has one active site, the turnover number is given by turnover number = R max [ E ] t = k 2 ( R max is often written as V max ) If the enzyme molecule has more than one active site, then [ E ] t is multiplied by the number of active sites to determine its effective concentration. Determine the value of the turnover number of the enzyme carbonic anhydrase, given that R max for carbonic anhydrase equals 249 μmol ⋅ L − 1 ⋅ s − 1 and [ E ] t = 2.23 nmol ⋅ L − 1 . Carbonic anhydrase has a single active site.

Explanation:

turn over number = R max / [E]t   = K2

From given , R max = 249 * 10 ^ -6 mol. L^-1

T [E]t = 2.23 n mol. L^-1

           =   2.23 * 10^-9 mol. L^-1

Putting values in above equation,

=          111.65 * 10^3           S^-1

Turn over number is maximum no of substrate molecule that can be converted into product molecules for unit time by enzyme molecule.

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."