Авидин

Использование

Avidin egg white was used in an assay using functionalized xenon as a biosensor to detect biotin-avidin binding. Egg white was used at 80 nmol.

Определение

A protein occurring in egg white, where it constitutes approximately 0.2% of the total protein. It has the property of combining firmly with biotin and rendering it unavailable to organisms, since proteolytic enzymes do not destroy the avidin–biotin complex. Avidin loses its ability to combine with biotin when subjected to heat; hence cooked egg white does not lead to biotin deficiency.

Общее описание

Avidin is a homotetrameric glycoprotein found in the egg white of birds, reptiles and amphibians. Each subunit is 16 kDa, singly glycosylated and binds to a molecule of biotin with greater affinity and specificity. Recombinant avidin from corn is similar to avidin from egg white in terms of properties like isoelectric point (pI) and antigenic properties except for the molecular weight. Avidin from corn has low molecular weight than chicken egg-derived avidin. This might be due to less complex glycosylation composition in plants. Commercial production of avidin from corn has certain advantages in terms of availability of greater biomass and avoiding the co-purification of animal virus.

Методы очистки

Avidin is purified by chromatography of an ammonium acetate solution on CM-cellulose [Green Biochem J 101 774 1966]. It is also purified by affinity chromatography on 2-iminobiotin-6-aminohexyl-Sepharose 4B [Orr J Biol Chem 256 761 1981]. Itis a biotin-binding protein.