アビジン

解説アビジン，卵白中に含まれるタンパク質で，ビオチンと特異的かつ強力に結合する．ニワトリの卵白中に0.06％ほど含まれる糖タンパク質の一種で，糖鎖にはマンノースおよびグルコサミンが含まれている。等電点pH約10の塩基性アルブミン様タンパク質で，結晶化され，アミノ酸配列が決定されている。四量体として存在し，分子量は約6万。ビオチン結合サイトを有するサブユニット4個からなる．アビジン-ビオチンの反応は抗原抗体反応に比べて速いので，アフィニティークロマトグラフィーによる生体成分の分離や放射標識のかわりにビオチン標識することにより，生体成分を高感度で検出することなどに利用されている．

天然物の起源ニワトリ卵白：25～152

使用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.

一般的な説明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.

純化方法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.

定義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.