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#hemocyanin

3 public questions tagged with this topic.

Animal Classification

Blood pigment in molluscs is usually

Molluscan blood pigment usually hemocyanin, copper-containing protein dissolved freely in plasma rather than enclosed in erythrocytes, forming blue color when oxygenated and colorless deoxygenated. Each functional unit contains two copper atoms coordinated by histidines reversibly binding one oxygen molecule, assembling into multi-decameric complexes with cooperative binding. Hemoglobin occurs in few freshwater bivalves and planorbid snails and some cephalopods as intracellular pigment, chlorocruorin primarily in some polychaete annelids, myoglobin muscular oxygen store. Hemocyanin predominates marine molluscs with low temperature tolerance, functioning efficiently under low oxygen and slightly alkaline hemolymph pH shared with arthropods.

Ref: Campbell Biology, 12th ed., Chapter 42: Molluscan Hemocyanin; NCERT Class 11, Chapter 7, Pigments

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Animal Classification

The most common respiratory pigment in arthropods is

Hemocyanin serves as predominant extracellular respiratory pigment in many arthropods, notably crustaceans, xiphosurans and arachnids, characterized by copper atoms each coordinated by histidines that reversibly bind one oxygen molecule, turning blue when oxygenated. Hexameric or multi-hexameric molecules are dissolved freely in hemolymph, not packaged in cells, exhibiting cooperative oxygen binding albeit lower affinity than hemoglobin iron-porphyrin complex in vertebrates. Hemoglobin occasionally occurs in some aquatic insects and crustaceans, chlorocruorin in some annelids, myoglobin in muscle. Hemocyanin adaptation suits low and fluctuating aquatic oxygen levels, temperature sensitivity and high hemolymph pH.

Ref: Campbell Biology, 12th ed., Chapter 42: Respiratory Pigments Hemocyanin; NCERT Class 11, Physiology

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UV-VIS spectroscopy

Which technique detects oxidation state of hemocyanin?

Hemocyanin, respiratory copper protein of arthropods and molluscs, binds oxygen via binuclear copper centers rather than iron heme. Deoxygenated Cu(I) form is essentially colorless with weak absorption, whereas oxy-hemocyanin with Cu(II)-peroxide complex exhibits intense ligand-to-metal charge transfer bands near 340 nm and 580 nm conferring characteristic blue color. These electronic transitions are quantifiable by UV-Visible absorption spectroscopy using Beer-Lambert law. Changes in band intensity and position report oxidation state, oxygen saturation and allosteric regulation. Fluorescence lacks suitable chromophore, mass spectrometry cannot monitor reversible oxygenation dynamically in solution.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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