Kozloff L M, Crosby L K, Baugh C M
J Virol. 1979 Nov;32(2):497-506. doi: 10.1128/JVI.32.2.497-506.1979.
Three types of reagents were used to determine the structural role and location of the polyglutamate portion of the Escherichia coli T4D bacteriophage baseplate dihydropteroyl hexaglutamate. These reagents were examined for their effect in vitro on some of the final steps in phage baseplate morphogenesis. The reagents were (i) a series of oligopeptides composed solely of glutamic acid residues but with various chemical linkages and chain lengths; (ii) a homogeneous preparation of carboxypeptidase G1, an exopeptidase that hydrolyzes carboxyl-terminal glutamates (or aspartates) from simple oligopeptides, including the gamma-glutamyl bonds on folyl polyglutamates as well as the bond between the carboxyl group of the p-aminobenzoyl moiety and the amino group of the first glutamic acid residue of folic acid; and (iii) antisera prepared against a polyglutamate hapten. All three types of reagent markedly inhibited the attachment of the phage long tail fibers to the baseplate. Other steps in baseplate assembly such as the addition of T4D gene 11 or gene 12 products were not affected by any of these reagents. These results indicate that the polyglutamate portion of the folate is located near the attachment site on the bacteriophage baseplate for the long tail fibers.
使用了三种试剂来确定大肠杆菌T4D噬菌体基板二氢蝶酰六谷氨酸中聚谷氨酸部分的结构作用和位置。检测了这些试剂在体外对噬菌体基板形态发生一些最终步骤的影响。这些试剂包括：(i) 一系列仅由谷氨酸残基组成但具有不同化学连接和链长的寡肽；(ii) 羧肽酶G1的纯化物，这是一种外肽酶，可从简单寡肽中水解羧基末端的谷氨酸（或天冬氨酸），包括叶酰聚谷氨酸上的γ-谷氨酰键以及对氨基苯甲酰部分的羧基与叶酸第一个谷氨酸残基的氨基之间的键；(iii) 针对聚谷氨酸半抗原制备的抗血清。所有这三种类型的试剂均显著抑制噬菌体长尾纤维与基板的附着。基板组装的其他步骤，如添加T4D基因11或基因12产物，均不受这些试剂的影响。这些结果表明，叶酸的聚谷氨酸部分位于噬菌体基板上长尾纤维的附着位点附近。
