Setlow P, Ozols J
J Biol Chem. 1980 Nov 10;255(21):10445-50.
The complete covalent structure of Protein B, the third major protein degraded during germination of Bacillus megaterium spores, has been determined. The intact protein was cleaved with the specific B. megaterium spore protease into three peptides, residues 1 to 31 (B-III), 32 to 66 (B-I), and 67 to 96 (B-II). Cleavage of the intact protein with trypsin allowed isolation of the peptide encompassing residues 61 to 77 (T-11) as well as the COOH-terminal peptide, residues 94 to 96 (T-4). Cleavage of Peptide B-I with trypsin or chymotrypsin allowed isolation of peptides encompassing residues 53 to 60 (B-I-T-2) and residues 52 to 66 (B-I-C-4), respectively. Subtractive Edman degradation of Peptide T-4, automated sequenator analysis of Peptides B-I, B-II, T-11, B-I-T-2, and B-I-C-4, previously published partial sequence data on the intact B-protein and carboxypeptidase V digestion of the intact protein provided the data from which the following unique sequence was deduced: NH2-Ala-Lys-Gln-Thr-Asn-Lys-Thr-Ala-Ser-Gly-Thr-Ser-Thr-Gln-His-15 Val-Lys-Gln-Gln-Asp-Ala-Gln-Ala-Ser-Lys-Asn-Asn-Phe-Gly-Thr-30 Glu-Phe-Gly-Ser-Glu-Thr-Asn-Val-Gln-Glu-Val-Lys-Gln-Gln-Asn-45 Ala-Gln-Ala-Ala-Asn-Lys-Ser-Gln-Asn-Ala-Gln-Ala-Ser-Lys-60 Asn-Asn-Phe-Gly-Thr-Glu-Phe-Ala-Ser-Glu-Thr-Ser-Ala-Gln-Glu-75 Val-Arg-Gln-Gln-Asn-Ala-Gln-Ala-Gln-Lys-Lys-Asn-Gln-Asn-90 Ser-Gly-Lys-Tyr-Gln-Gly-COOH. The primary sequence of the B-protein contains a large internal duplication (residues 17 to 50 and 52 to 85), and shows significant sequence homology with the A- and C-proteins, the other major proteins degraded during B. megaterium spore germination.
巨大芽孢杆菌孢子萌发过程中第三种主要降解蛋白B的完整共价结构已被确定。完整的蛋白被巨大芽孢杆菌孢子特异性蛋白酶切割成三个肽段，分别是1至31位残基（B-III）、32至66位残基（B-I）和67至96位残基（B-II）。用胰蛋白酶切割完整蛋白可分离出包含61至77位残基的肽段（T-11）以及羧基末端肽段，即94至96位残基（T-4）。用胰蛋白酶或胰凝乳蛋白酶切割肽段B-I可分别分离出包含53至60位残基的肽段（B-I-T-2）和包含52至66位残基的肽段（B-I-C-4）。对肽段T-4进行减法埃德曼降解、对肽段B-I、B-II、T-11、B-I-T-2和B-I-C-4进行自动测序仪分析、之前发表的关于完整B蛋白的部分序列数据以及对完整蛋白进行羧肽酶V消化，这些数据推导出了以下独特序列：NH2-丙氨酸-赖氨酸-谷氨酰胺-苏氨酸-天冬酰胺-赖氨酸-苏氨酸-丙氨酸-丝氨酸-甘氨酸-苏氨酸-丝氨酸-苏氨酸-谷氨酰胺-组氨酸-15缬氨酸-赖氨酸-谷氨酰胺-谷氨酰胺-天冬氨酸-丙氨酸-谷氨酰胺-丙氨酸-丝氨酸-赖氨酸-天冬酰胺-天冬酰胺-苯丙氨酸-甘氨酸-苏氨酸-30谷氨酸-苯丙氨酸-甘氨酸-丝氨酸-谷氨酸-苏氨酸-天冬酰胺-缬氨酸-谷氨酰胺-谷氨酸-缬氨酸-赖氨酸-谷氨酰胺-谷氨酰胺-天冬酰胺-45丙氨酸-谷氨酰胺-丙氨酸-丙氨酸-天冬酰胺-赖氨酸-丝氨酸-谷氨酰胺-天冬酰胺-丙氨酸-谷氨酰胺-丙氨酸-丝氨酸-赖氨酸-60天冬酰胺-天冬酰胺-苯丙氨酸-甘氨酸-苏氨酸-谷氨酸-苯丙氨酸-丙氨酸-丝氨酸-谷氨酸-苏氨酸-丝氨酸-丙氨酸-谷氨酰胺-谷氨酸-75缬氨酸-精氨酸-谷氨酰胺-谷氨酰胺-天冬酰胺-丙氨酸-谷氨酰胺-丙氨酸-谷氨酰胺-赖氨酸-赖氨酸-天冬酰胺-谷氨酰胺-天冬酰胺-90丝氨酸-甘氨酸-赖氨酸-酪氨酸-谷氨酰胺-甘氨酸-COOH。B蛋白的一级序列包含一个大的内部重复序列（17至50位残基和52至85位残基）,并且与A蛋白和C蛋白具有显著的序列同源性，A蛋白和C蛋白是巨大芽孢杆菌孢子萌发过程中其他主要的降解蛋白。
