Jaurin B, Grundström T
Proc Natl Acad Sci U S A. 1981 Aug;78(8):4897-901. doi: 10.1073/pnas.78.8.4897.
A 1536-nucleotide-long sequence that carries the ampC beta-lactamase gene of the Escherichia coli K-12 chromosome has been determined. This gene codes for a protein of 377 amino acids, of which the first 19 amino acids form a signal peptide. The molecular weight of the mature enzyme was determined to be 39,600. The ampC beta-lactamase with a substrate specificity for cephalosporins showed no significant sequence homologies with beta-lactamases of the penicillinase type or with D-alanine carboxypeptidases. However, because the region around serine-80 of the ampC beta-lactamase has extensive homology with an active-site fragment of the Pseudomonas aeruginosa cephalosporinase, we suggest that the ampC cephalosporinase as well as related cephalosporinases form a distinct group of serine beta-lactamases that have an evolutionary origin different from that of the serine penicillinases and thus constitute a new class of beta-lactamases.
已确定了一段1536个核苷酸长的序列，它携带大肠杆菌K - 12染色体的ampCβ-内酰胺酶基因。该基因编码一种由377个氨基酸组成的蛋白质，其中前19个氨基酸构成一个信号肽。成熟酶的分子量测定为39,600。对头孢菌素具有底物特异性的ampCβ-内酰胺酶与青霉素酶类型的β-内酰胺酶或D -丙氨酸羧肽酶没有明显的序列同源性。然而，由于ampCβ-内酰胺酶丝氨酸80周围区域与铜绿假单胞菌头孢菌素酶的活性位点片段有广泛的同源性，我们认为ampC头孢菌素酶以及相关的头孢菌素酶形成了一类独特的丝氨酸β-内酰胺酶，其进化起源与丝氨酸青霉素酶不同，因此构成了一类新的β-内酰胺酶。
