Synthetic and Conformational Studies of Active Site Peptides of Amino Acid Racemases

D-丙氨酸，一种细菌细胞壁肽-deglycan的基本常量，是由L-丙氨酸在氨基酸细胞的调节下进行生物合成的。Amog the amino acid racemase， a thermostable alanine racemase， a thermostable alanine racemase，a a thermostable alanine racemase，b B and dal genes fromSalmonella typhimurium编码，a amino acid racemase from Pseudomonas striata相对良好地研究酶。在赖氨酸居住者与该共因子pyridoxal phosphate链接的氨基酸序列被依赖于跟随的地方。stearothermophilus ：Ala-Val Val-Lys-Asn-Asn-Ala-Tyr（前序列：Ala-Pro-Pro-Lys-Ala-Asn-Ala-Tyr） ;沙门氏菌： dad B Val-Trp-Ser-Val-Lys-Ala-Asn-Ala-Tyr-Gly-His-Gly-Ile， dal Leu-Val-Val-Lys Ala-Asn-Ala-Tyr-Gly-His-Gly-Leu; P. striata ：Leu-Thr-Ala-Val-Leu-Lys-Ala-Ala-Asp-Ala-Try-Gly-His-Gly-Ile.在开发新的抑制剂中实现基本概念（antibacterial agents），我们开始了对活性站点肽的合成和规范性研究，作为模型活性站点。首先，我们比较了氨基酸序列，并将几个片段肽中的序列分开。The synthetic fragment peptides were then condensed to give protected of octapeptides的两种化合物和三种化合物of tetradecapeptides。所有的合成过程都是在解决方案阶段完成的。在N-保护性组转化为N-乙酰组之后，保护性组被去除，然后被三甲基磺酰三氟酯-三苯胺系统的处理，以给予两个八度和三个四乙酰乙酰衍生物的氨基酸序列的活性位点的相应反应。使用核磁共振光谱仪进行Boc-Leu-Thr-Ala-Val-Leu-OMe和Boc-Ala-Pro-Lys（Z）-Ala-Asn-Ala-Tyr（Bzl）-OBzl也进行了实验研究。

D-alanine, an essential constituent of bacterial cell wall pepti-deglycan, is biosynthesized from L-Alanine by the mediation of amino acid racemase. Amog the amino acid racemase, a thermostable alanine racemase from Bacillus stearothermophilus, two alanine racemases coded by dad B and dal genes fromSalmonella typhimurium, and amino acid racemase from Pseudomonas striata were relatively well studied enzymatically. The amino acid sequences around the lysine residue to which the cofactor pyridoxal phosphate linked were elucidated as follows.B. stearothermophilus : Ala-ValーVal-Lys-Asn-Asn-Ala-Tyr (former sequence : AlaーPro-ProーLys-Ala-Asn-Ala-Tyr) ; Salmonella typhimurium : dad B Val-Trp-Ser-Val-ValーLys-Ala-Asn-Ala-Tyr-Gly-His-Gly-Ile, dal Leu-Val-Ala-Val-Val-Lys Ala-Asn-Ala-Tyr-Gly-His-Gly-Leu ; P. striata : Leu-Thr-Ala-Val-Leu-Lys-Ala-Ala-Asp-Ala-Try-Gly-His-GlyーIle.In order to obtain the basic concept in developing new inhibitor (antibacterial agents), We started the synthetic and conformational studies of active site peptides of these enzymes as model active site. At first, we compared the amino acid sequences and divided the sequences in several fragment peptides. The synthetic fragment peptides were then condensed to give protected two kinds of octapeptides and three kinds of tetradecapeptides. All the synthetic procedures were performed in the solution phase. After the N-protective group was converted to N-acetyl group, the protective groups were then removed by treatment of trimethylsilyltriflate-thioanisole system to give acetyl derivatives of two octa-and three tetradecapeptides corresponding to the amino acid sequences of active sites of above mentioned racemases. The conformational studies using NMR spectroscopy for Boc-Leu-Thr-Ala-Val-Leu-OMe and Boc-Ala-Pro-Pro-Lys (Z) -Ala-Asn-Ala-Tyr (Bzl) -OBzl were also performed.