Romanova A K, Zhen-Qi-Cheng Z, McFadden B A
Institute of Soil Science and Photosynthesis R.A.S., Pushchino Moscow region, Russia.
Biochem Mol Biol Int. 1997 Jun;42(2):299-307. doi: 10.1080/15216549700202691.
The values of molecular carboxylase activity kcat and carboxylation specificity factor tau for mutant ribulose 1,5-bisphosphate carboxylase (rubisco) from Anacystis nidulans decreased as compared to those of the wild type recombinant rubisco. The substitution of five amino acid residues in rubisco large subunit Lys,Ala,Ser,Thr,Leu(339-343)Phe,Leu,Met,Ile,Lys had kcat decreased by 90% and tau by 36.3%. The same parameters for mutants with the single replacements decreased: for Thr342Ile kcat by 40.5% and tau by 16.7%, and for mutant Leu343Lys kcat by 48.1% and tau by 18.5%. Mutant rubisco with three amino acid residues changed Val,Asp,Leu(346-348)Tyr,His,Thr was inactive. The substitution Leu326Ile decreased kcat by 54.4% and tau by 34.2%; and change Ser328Ala decreased kcat only by 5.6% but tau by 41.5%. Replacement Asn123His decreased kcat by 16.5%. Significance of the non conservative amino acid residues for carboxylase activity and ribulose-1,5-bisphosphate partition is discussed.
与野生型重组核酮糖-1,5-二磷酸羧化酶（rubisco）相比，来自集胞藻6803的突变型rubisco的分子羧化酶活性kcat和羧化特异性因子tau的值降低。rubisco大亚基中五个氨基酸残基Lys、Ala、Ser、Thr、Leu(339 - 343)被Phe、Leu、Met、Ile、Lys取代后，kcat降低了90%，tau降低了36.3%。单取代突变体的相同参数也降低：对于Thr342Ile，kcat降低了40.5%，tau降低了16.7%；对于突变体Leu343Lys，kcat降低了48.1%，tau降低了18.5%。具有三个氨基酸残基改变Val、Asp、Leu(346 - 348)被Tyr、His、Thr取代的突变型rubisco无活性。Leu326Ile取代使kcat降低了54.4%，tau降低了34.2%；Ser328Ala改变仅使kcat降低了5.6%，但tau降低了41.5%。Asn123His取代使kcat降低了16.5%。讨论了非保守氨基酸残基对羧化酶活性和核酮糖-1,5-二磷酸分配的重要性。
