The ligand system present in vitamin B12 is:
Corrin is a heterocyclic compound. It is the parent macrocycle related to the substituted derivative that is found in vitamin B12. Its name reflects that it is the "core" of vitamin B12 (cobalamins)
Superoxide dismutase contains the metal ions:
The oxidation state of iron in methemoglobin is:
The correct set of the biologically essential elements, is:
Patients suffering from Wilson’s disease have:
High dose of dietary supplement ZnSO4 for the cure of Zn deficiency:
The extent of π electron conjugation in macrocyclic rings of (i) heme, (ii) coenzyme B12 and (iii) chlorophyll follows the order:
Least conjugation is present in Vitamin B12 as one side of the corrin ring doesn’t have methylene linkages. In Heme, there is extensive conjugation of π electron (11 π ) as compared to that of chlorophyll.( 10π )
The number of histidine amino acid nitrogen atoms coordinated to bimetallic active site of oxyhemocyanin and oxyhemerythrine, respectively, are:
The biological functions of carbonic anhydrase and Carboxypeptidase A, respectively, are
The Fe—Npprphyrin bond distances in the deoxy and oxy-hemoglobin, respectively are:
The biological functions of the cytochrome P450 and myoglobin are, respectively:
Correct Answer :- a
Explanation : Cytochromes P450 (P450) are hemoproteins encoded by a superfamily of genes nearly ubiquitously distributed in different organisms from all biological kingdoms. The reactions carried out by P450s are extremely diverse and contribute to the biotransformation of drugs, the bioconversion of xenobiotics, the bioactivation of chemical carcinogens, the biosynthesis of physiologically important compounds such as steroids, fatty acids, eicosanoids, fat-soluble vitamins and bile acids, the conversion of alkanes, terpenes and aromatic compounds as well as the degradation of herbicides and insecticides. Cytochromes P450 belong to the group of external monooxygenases and thus receive the necessary electrons for oxygen cleavage and substrate hydroxylation from different redox partners. The classical as well as the recently discovered P450 redox systems.
Myoglobin contains a heme (prosthetic) group which is responsible for its main function (carrying of oxygen molecules to muscle tissues). Myoglobin can exist in the oxygen free form, deoxymyoglobin, or in a form in which the oxygen molecule is bound, called oxymyoglobin. Myoglobin is a protein found in muscles that binds oxygen with its heme group like hemoglobin.
Oxidation of the iron atom (Fe2+ -> Fe3+) is mainly responsible for the color of muscle and blood.
Hemocyanin, a copper-containing protein chemically unlike hemoglobin, is found in some crustaceans.
Hemocyanin is blue in colour when oxygenated and colourless when oxygen is removed.
The reduction of nitrogen to ammonia, carried out by the enzyme nitrogenase, needs:
In bacterial ruberdoxin, the number of iron atoms, sulfur bridges and cysteine ligands are:
A metal ion that replace manganese (II) ion in Mangano–proteins without changing its function, is:
The changes (from A–D given below) which occur when O2 binds to hemerythrin are:
(A) One ion atom is oxidized.
(B) Both the iron atoms are oxidized.
(C) O2 binds to one iron atom and is also hydrogen bonds.
(D) O2 binds to both the iron atoms and is also hydrogen bonded.
Amongst the following, the group that is bound to the metal ion in cenzyme B12 is:
Based on the behavior of the metalloenzymes, consider the following statements:
(A) In the enzymes, the zinc act ivates O2 to form peroxide species.
(B) In the enzymes, the zinc activates H2O and provides a zinc bound hydroxide.
(C) In the enzymes, the zinc activates O2 to break the bounding between the two oxygens.
(D) Zincion acts as a nucleophile and attacks at the peptide carbonyl.
The set of correct statements is,
Fe2+ -porphyrins fail to exhibit reversible oxygen transport and cannot differentiate CO from O2. However, the hemoglobin is free from both these pit falls. Among the following the correct set of statements is:
(A) Fe2+-porphyrins undergo μ-oxodimer formation and the same is prevented in case of the hemoglobin.
(B) Fe–CO bond strength is much low in case of hemoglobin when compared to the Fe2+ -porthyrins.
(C) While Fe–CO is linear, Fe–O2 is bent and is recognized by hemoglobin.
(D) The interlinked four monomeric units in the hemoglobin are responsible to overcome the pitfalls.