Feller G, Thiry M, Gerday C
Laboratory of Biochemistry, University of Liège, Belgium.
DNA Cell Biol. 1991 Jun;10(5):381-8. doi: 10.1089/dna.1991.10.381.
The lip2 gene from the antarctic psychotroph Moraxella TA144 was sequenced. The primary structure of the Lip2 preprotein deduced from the nucleotide sequence is composed of 433 amino acids with a predicted Mr of 47,222. This enzyme contains a Ser-centered consensus sequence and a conserved His-Gly dipeptide found in most lipase amino-terminal domains. These sequences are involved in the lipase active site conformation since substitution of the conserved Ser or His residues by Ala and Gln, respectively, results in the loss of both lipase and esterase activities. Structural factors that would allow proper enzyme flexibility at low temperatures are discussed. It is suggested that only subtle changes in the primary structure of these psychrotrophic enzymes can account for their ability to catalyze lipolysis at temperatures close to 0 degrees C.
对来自南极嗜冷菌莫拉氏菌TA144的lip2基因进行了测序。从核苷酸序列推导的Lip2前体蛋白的一级结构由433个氨基酸组成，预测分子量为47222。这种酶含有一个以丝氨酸为中心的共有序列和一个在大多数脂肪酶氨基末端结构域中发现的保守的组氨酸-甘氨酸二肽。这些序列参与脂肪酶活性位点的构象形成，因为分别用丙氨酸和谷氨酰胺取代保守的丝氨酸或组氨酸残基会导致脂肪酶和酯酶活性丧失。讨论了在低温下允许酶具有适当灵活性的结构因素。有人提出，这些嗜冷酶一级结构中只有细微的变化就能解释它们在接近0摄氏度的温度下催化脂肪分解的能力。
