Distribution of D-Amino acids in Aquatic Animals

D-氨基酸通常被认为是天然的奇特物质。然而，最近的研究表明，一些D-氨基酸在微生物、植物和高等动物中的分布相当广泛。本研究从软体动物、节肢动物、棘皮动物、原脊椎动物和脊椎动物5门37种组织中提取丙氨酸D-对映体的80%乙醇提取物。用两种不同的方法测定提取物中D-丙氨酸的浓度：1)用氨基酸自动分析仪测定与D-氨基酸氧化酶(EC 1.4.3.3)孵育前后提取物中的丙氨酸；2)在手性毛细管柱上用气相色谱分析丙氨酸的三氟乙酰1-丙基衍生物。显著的D-丙氨酸含量(150-820毫克，D-丙氨酸浓度以每100克组织中毫克为单位)。在一些海洋双壳类动物的肌肉中检测到，如mac…更多的是中国贝类，Spisura sachalinens，Tresus keenae，Perondia venulosa，和Meretrix lusoria，但不是在海洋双壳类，如Amuium Japan onicum，Scapharca broughtonii，Patinopecten yessoensis，Atrina ectinata，Ostrea edulis的肌肉中。在所有含有D-丙氨酸的物种中，D-丙氨酸的浓度远高于L异构体。在一种微咸的双壳类贝类的软体部分也发现了41毫克的D-丙氨酸。值得注意的是，含D-丙氨酸的双壳类属于异齿目，缺D-丙氨酸的双壳类属于翼形目。在腹足类和头足类中没有检测到D-丙氨酸的含量。在所分析的所有甲壳类物种的肌肉中，都发现了D-丙氨酸。虽然D-丙氨酸与总丙氨酸的浓度比(D/D+L)在0.3~0.4之间，但D-丙氨酸的水平是不同的，从美洲好鱼的10 mg到中华绒螯蟹的260 mg不等。在两种海胆的性腺中均检测到相当数量的氨基酸，其D/D+L比值分别为0.72和0.47。罗氏海鞘和五种鱼的肌肉中不含D-丙氨酸。较少

D-amino acids are generally viewed as natural oddities. However, recent investigations show a rather wide distribution of some D-amino acids in microbes, plants and higher animals. The present studies were planned to accumulate more information on the distribution of D-enantiomer of alanine in aquatic animals.Eighty percent ethanol extracts were prepared from tissues of 37 species in 5 phyla (Mollusca, Arthropoda, Echinodermata, Prochordata, and Vertebrata). The concentration of D-alanine in the extracts was determined in two different ways: 1) measuring alanine in the extract before and after incubation with D-amino acid oxidase (EC 1.4.3.3) by an amino acid autoanalyzer and 2) analyzing as trifluoroacetyl 1-propyl derivatives of alanine by gas chromatography on a capillary column of chiracil-Val.Significant amounts of D-alanine (150-820 mg, The concentration of D-alanine is expressed in terms of mg per 100 g of tissue.) were detected in the muscles of some marine bivalves such as Mac … More tra chinensis, Spisura sachalinensis, Tresus keenae, Peronidia venulosa, and Meretrix lusoria but not in the muscles of marine bivalves such as Amusium Japonicum, Scapharca broughtonii, Patinopecten yessoensis, Atrina pectinata, and Ostrea edulis. In all the D-alanine-containing species, the concentration of D-alanine was much higher than that of L-isomer. Forty one mg of D-alanine was also found in the soft part of a brackish bivalve Corbicula leana. It is noteworthy that D-alanine-containing bivalves belong to the order Heterodonta and D-alanine-lacking bivalves to the order Pteriomorphia. No measurable quantity of D- alanine could be detected in gastropods and cephalopods. In the muscles of all the crustacean species analyzed, D-alanine was found. The level of the amino acid was variable, ranging from 10 mg in Homarus americanus to 260 mg in Eriocheir sinensis, although concentration ratio of D-alanine to total alanine (D/D+L) was between 0.3 and 0.4. Sizable amount of the amino acid was detected in the gonad of both species of sea urchins Hemicentrotus pulcherrimus (90 mg) and Anthrocidaris crassispina (170 mg) and their D/D+L ratios were 0.72 and 0.47, respectively. The muscle of ascidian Halocynthia roretzi and five species of fishes did not contain D-alanine. Less