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Oxidized form of enzyme Catalase (structure A); prepared by the reaction of [Fe(P)]+ (P = porphyrin) with H2O2 has a green color because of:
A (substituents on ring are removed for clarity)
At pH 7, the zinc(II) ion in carbonic anhydrase reacts with CO2 to give:
Molybdoenzymes can both oxidize as well as reduce the substrates, because:
Under physiological condition, oxygen is binding to deoxyhemoglobin and deoxymyoglobin, the binding curve and its pH dependence, respectively, are:
Match the metalloproteins in column A with their function in column B
The correct answer is
The total number of metal ion and the number of coordinated imidazole units of histidine in the active site of oxy-hemocyanin, respectively, are:
The changes (from A-D given below) which occur when O2 binds to hemerythrin are
(A) One iron atom is oxidized
(B) Both the iron atoms are oxidized
(C) O2 binds to one iron atom and is also hydrogen-bonded.
(D) O2 binds to both the iron atoms and is also hydrogen-bonded.
The resonance Raman stetching frequency of (V0-0 in cm-1) of is 1580. The V0-0 for O2 in bound oxy-hemoglobin is close to:
The metal present at the active site of the protein Carboxypept idase A is:
Match the following items of column I with the appropriate items in column II
In biological systems, the metal ion involved in the dioxygen transport besides Fe is:
Iron–sulphur clusters in bio logical systems are involved in:
The amino acid side chain high affinity for Ca2+ and Cu2+ in metallo–proteins is:
When a reduced cytochrome transfers an electron from its Fe(II) to the bound O2:
In photosynthesis, the predominant metal present in the reaction centre of photo –system II is:
Metals exert important functions in the chloroplast of plants, where they act as cofactors and catalysts in the photosynthetic electron transport chain. In particular, manganese (Mn) has a key function because of its indispensable role in the water-splitting reaction of photosystem II (PSII).
Zn in carbonic anhydrase is coordinated by three histidine and one water molecule. The reaction of CO2 with this enzyme is an example of:
CO2 acts as an electrophile and H2O as a nucleophile which attacks CO2. Hence, electrophilic addition takes place.
In biological systems, the metal ions involved in electron transport are:
In the transformation of oxyhaemoglobin to deoxyhaemoglobin:
Among the following pair of metal ions present in Nature. The first one functions as an electron transfer agent and the second one catalyzes the hydrolysis reactions. The correct pair is:
A well known naturally occurring organometallic compound is:
The red color of oxyhaemoglobin is mainly due to the:
Each hemoglobin protein is made up subunits called hemes, which are what give blood its red color. More specifically, the hemes can bind iron molecules, and these iron molecules bind oxygen. The blood cells are red because of the interaction between iron and oxygen i.e. intra ligand π–π* transition.
When the iron is oxygenated(Fe+3), it becomes red. When the iron is deoxygenated(Fe+2), it becomes blue. This is why your veins are blue.
Hemoglobin is an oxygen carrying. The correct statement about oxy–hemoglobin is that:
Oxymyoglobin Mb(O2) and oxyhaemoglobin Hb(O2)4, respectively, are:
The number of oxygen molecule(s) that a molecule of hemerythrin can transport is:
Mg2+ is preferred in photosynthesis by chlorophyll because:
Among the given pH values, the O2 binding efficiency of hemoglobin is maximum at:
Identify the function of hemocyanin and the metal responsible for it:
During oxygen transport by hemerythrin, oxygen is bound as:
The mechanism of dioxygen binding is unusual. Most O2 carriers operate via formation of dioxygen complexes, but hemerythrin holds the O2 as a hydroperoxide (HO2, or -OOH−). The site that binds O2 consists of a pair of iron centres. The iron atoms are bound to the protein through the carboxylate side chains of a glutamate and aspartates as well as through five histidine residues. Hemerythrin and myohemerythrin are often described according to oxidation and ligation states of the iron center:
Fe3+—OH—Fe3+— (any other ligand)met (oxidized)
The uptake of O2 by hemerythrin is accompanied by two-electron oxidation of the diferrous centre to produce a hydroperoxide (OOH−) complex. The binding of O2 is roughly described in this diagram:
At pH 7.2 and 10 Torr oxygen partial pressure, the extent of O2 binding is: