Post X‐ray crystallographic studies of chymosin: the existence of two structural forms and the regulation of activity by the interaction with the histidine‐proline cluster of κ‐casein

FEBS Letters

Majer, Pavel³  Rumsh, Lev²  Gustchina, Elena²  Andreeva, Natalia¹  Ginodman, Lev² 

[1] Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia;Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia;Structural Biochemistry Program, National Cancer Institute, Frederick, MD 21702, USA

关键词: Chymosin;    Aspartic proteinase;    Three-dimensional structure;    Chymosin specificity;    Chymosin activation;    Allosteric activator;    Fmoc;    9-fluorenylmethyloxy carbonyl;    HBTU;    2;    (1H-benzotriazole-1-yl)-1;    1;    3;    3-tetramethyluronium hexafluorophosphate;    HOBt;    N-hydroxy benzotriazole;    NMP;    N-methyl pyrolidone;    TFA;    trifluoroacetic acid;   

DOI  :  10.1016/0014-5793(95)01488-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Calf chymosin molecules exist in the two alternative structural forms: the first one has S₁ and S₃ binding pockets occluded by its own Tyr⁷⁷ residue (the self-inhibited form); the second has these pockets free for a substrate binding (the active form). The preliminary incubation of the enzyme with a pentapeptide corresponding to the histidine-proline cluster of the specific substrate κ-casein results in a 200-fold increase of the hydrolysis rate for the enzyme ‘slow substrate’. The result suggests that the cluster is an allosteric effector that promotes the conversion of the enzyme into the active form. These data provide the experimental ground for the explanation of chymosin specificity towards κ-casein.

【 授权许可】

Unknown