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#serum

2 public questions tagged with this topic.

Which is NOT a function of albumin in serum?

Bovine serum albumin commonly abbreviated BSA sixty six point five kilodalton 585 amino acid residues after cleavage N-terminal signal peptide twenty four amino acids, three homologous domains I II III each divided into two subdomains A B stabilized by total seventeen disulfide bonds forming heart-shaped globular structure approximately eighty by eighty by thirty angstroms with hydrophobic pockets located in subdomains IIA site one also known as warfarin binding site and IIIA site two ibuprofen binding site that transport hydrophobic molecules: long chain fatty acids oleic acid palmitic acid at five to seven sites increasing solubility ten thousand fold, bilirubin product heme catabolism preventing kernicterus, thyroxine T4 thyroid hormone, steroid hormones cortisol, metal ions copper nickel via N-terminal metal binding ATCUN motif Asp Ala His, drugs warfarin ibuprofen altering pharmacokinetics. Buffering function due imidazole side chains sixteen histidine residues pKa around six providing 20 percent of plasma buffering capacity at neutral pH scavenging protons. Antioxidant capacity via free thiol at cysteine thirty four 0.

Ref: Peters Plasma Proteins 1996 albumin 66.5 kDa transport buffering antioxidant; Lodish MBoC albumin no RGD attachment blocking ELISA.

Which component provides iron transport in serum?

Iron necessity stems from essential cofactor roles in fundamental enzymes: ribonucleotide reductase small subunit R2 contains diferric tyrosyl radical centre essential for reducing ribonucleoside diphosphate to deoxyribonucleotide required for DNA replication and repair, cytochrome c oxidase complex IV contains heme a3 plus copper facilitating electron transport to oxygen, and aconitase iron-sulfur cluster catalyzing tricarboxylic acid cycle. Free ferric iron Fe3+ precipitates as insoluble Fe(OH)3 at neutral pH solubility product extremely low 10^-38, and participates in Fenton reaction Fe2+ plus H2O2 producing hydroxyl radical OH extremely reactive damaging DNA strand breaks and lipid peroxidation. Transferrin family 80 kDa bilobed glycoprotein synthesized by hepatocytes and secreted into plasma at 2 to 3 milligrams per ml, each lobe N and C lobe binds one Fe3+ ion plus synergistic carbonate anion coordinating octahedrally via two tyrosines, one histidine, one aspartate, forming complex with extremely low dissociation constant 10^-22 M keeping iron soluble and redox inert protected inside binding cleft.

Ref: Crichton Iron Metabolism 2016 transferrin Fe3+ transport 80 kDa; Alberts MBoC TfR1 clathrin endocytosis ribonucleotide reductase.