褐飞虱对游离氨基酸的利用

通过测定褐飞虱虫体、蜜露及稻株中16种游离氨基酸的含量及百分率组成,并进行对比分析,初步探讨了褐飞虱对游离氨基酸的利用问题。虫体、蜜露和稻株中含量最多的氨基酸分别为丙氨酸、天门冬氨酸和谷氨酸。褐飞虱大量吸收的氨基酸是丙氨酸,稻株中含量最少的蛋氨酸和酪氨酸,在蜜露中检测不到,认为可全部被吸收利用;相反,天门冬氨酸则很少被利用,谷氨酸被利用的相对量也不多;其他氨基酸或多或少地为褐飞虱所利用。     

松阿扁叶蜂越冬幼虫体内氨基酸含量的测定分析

本文测定了不同时期松阿扁叶蜂Acantholyda posticalis Matsumura越冬幼虫虫体、血淋。巴内氨基酸含量,并对影响幼虫抗寒的氨基酸进行了探讨。对越冬幼虫体内17种氨基酸的研究结果表明,从越冬初期至越冬期,氨基酸种类并没有发生变化,但各种氨基酸含量变化不同,丙氨酸、谷氨酸、脯氨酸、精氨酸和胱氨酸随着温度的下降呈增加趋势。幼虫虫体总氨基酸含量增幅最大的为丙氨酸,比越冬初期增加了28.8%,其次是脯氨酸、酪氨酸、苯丙氨酸,分别比越冬初期增加了9.4%、6.4%和5.4%,其他氨基酸增加不明显;幼虫血淋巴内游离氨基酸中的丙氨酸、胱氨酸和谷氨酸含量分别比越冬初期增加了94.6%、80.2%和19.6%。因此认为体内这些氨基酸含量的变化可能与低温抗寒密切相关。     

龙眼肉干制过程氨基酸组分分析

利用氨基酸自动分析仪分别测定加工前后的龙眼肉中的总氨基酸和游离氨基酸含量。结果,干制前后龙眼肉的氨基酸种类没有差别,但含量有明显差别,多数氨基酸的含量在干制后明显下降。结论:除丙氨酸和甲硫氨酸外,干制后的龙眼肉中的总氨基酸和游离氨基酸含量比干制前有明显下降,其中以碱性、酸性氨基酸含量的下降尤其显著。该差异可能是由于干制过程中发生美拉德反应造成的。     

小菜蛾感染球孢白僵菌后血淋巴游离氨基酸的测定

通过高效液相色谱（HPLC）对感染球孢白僵菌后小菜蛾血淋巴游离氨基酸含量进行测定,结果表明染菌后小菜蛾幼虫体内氨基酸含量明显低于对照组,主要是由于菌株在虫体内营养生长消耗和虫体内的养分所致;小菜蛾幼虫体内具有菌株营养生长所必需的氨基酸,因此可以认为小菜蛾是白僵菌的敏感寄主;各处理组间各种游离氨基酸在量上存在一定的差异,是由于不同发育阶段的虫体与菌株及不同类型菌株营养生长所必需的游离氨基酸含量不同所造成的。     

氨基酸代谢调控在大鳞副泥鳅应对氨暴露中的作用

将大鳞副泥鳅(Paramisgurnus dabryanus)暴露于30 mmol/L NH4Cl溶液中以研究高浓度环境氨对其血浆、肝脏及肌肉组织中游离氨基酸含量的影响。氨暴露会显著影响大鳞副泥鳅血浆、肝脏及肌肉组织中游离氨基酸含量(P0.05)。随着氨暴露时间的延长,大鳞副泥鳅血浆中丙氨酸的含量显著增加,且显著高于对照组(P0.05)。在氨暴露12h后,其肝脏组织中游离谷氨酸含量显著上升(P0.05),而在暴露72h后迅速下降(P0.05)。而游离丙氨酸含量在氨暴露的前24h内基本保持恒定,随后开始显著上升(P0.05)并持续至72h。在氨暴露大鳞副泥鳅12h后,肌肉中游离谷氨酸含量显著上升(P0.05),随后快速下降至初始水平并持续到实验结束(P0.05),且在暴露72h和96h时显著低于对照组(P0.05)。肌肉中游离丙氨酸含量随着氨暴露时间的延长呈现先上升后降低的趋势,并在暴露12h和48h时出现2个峰值,且显著高于对照组(P0.05)。在氨暴露下,其血浆、肝脏及肌肉中游离谷氨酸含量显著降低,且谷氨酰胺含量和谷氨酰胺合成酶活性显著提高,说明在高环境氨条件下,大鳞副泥鳅会利用谷氨酰胺合成酶将谷氨酸和NH_4~+合成无毒的谷氨酰胺以降低氨毒性。随着氨暴露时间的延长,大鳞副泥鳅血浆和组织有明显的丙氨酸累积且游离谷氨酸、精氨酸和脯氨酸含量显著降低,说明其可通过代谢这些特定氨基酸生成丙氨酸以降低体内氨的累积。     

氮、磷、钾营养对膜荚黄芪幼苗根系活力和游离氨基酸含量的影响

运用水培试验法研究不同营养水平对黄芪幼苗根系活力和游离氨基酸组成及含量的影响。结果表明:缺素显著降低黄芪根系活力,不同营养处理游离氨基酸含量差异显著,游离氨基酸总量的变化规律为叶片>根,各处理游离氨基酸总量为-K>-P>NPK>-N。全素处理与缺素处理相比,能提高根系活力、协调根冠比。黄芪幼苗通过提高体内游离氨基酸含量以增强对营养胁迫逆境的适应能力。     

甘蔗组织中游离氨基酸组分和含量研究

在甘蔗幼苗中,各个器官的丙氨酸含量都比较高,但在完全展开叶的叶片和叶鞘中丝氨酸含量更高;游离氨基酸总量的分布为完全展开叶叶片》完全展开叶叶鞘,苗根>心叶、幼茎,在伸长盛期和工艺成熟前期9个甘蔗基因型+1叶均以丙氨酸占优势。不同基因型的各种游离氨基酸含量都有明显的差异。在工艺成熟前期,早熟基因型的游离氨基酸总量比较低。伸长盛期与工艺成熟前期游离氨基酸总量之比值也与不同基因型的熟性密切相关,中晚熟品种的明显较低.早熟品种的较高,三个细茎早熟原种材料的更高。     

氮、磷、钾营养对膜荚黄芪幼苗根系活力和游蓠氨基酸含量的影响

运用水培试验法研究不同营养水平对黄芪幼苗根系活力和游离氨基酸组成及含量的影响。结果表明：缺素显著降低黄芪根系活力,不同营养处理游离氨基酸含量差异显著,游离氨基酸总量的变化规律为叶片〉根,各处理游离氨基酸总量为-K〉-P〉NPK〉-N。全素处理与缺素处理相比．能提高根系活力、协调根冠比。黄芪幼苗通过提高体内游离氨基酸含量以增强对营养胁迫逆境的适应能力。     

中华绒螯蟹不同部位游离氨基酸的测定与分析

本文对中华绒螯蟹不同部位的游离氨基酸含量和组成进行测定,结果显示：中华绒螯蟹步足肌肉、腹部肌肉和蟹黄这三个部位的游离氨基酸总量、呈味氨基酸总量、必需氨基酸总量和限制性氨基酸总量存在显著差异性。此外,阳澄湖蟹和池塘养殖蟹的各部位游离氨基酸含量和组成也存在很大差异性。     

冷藏对米蛾卵液中游离氨基酸变化的影响

赤眼蜂的工厂化繁育常使用米蛾卵作为中间寄主卵,为了满足赤眼蜂生产的需要,需对米蛾卵进行冷藏,但冷藏米蛾卵影响赤眼蜂的生长发育。利用核磁共振技术(NMR)测定了新鲜米蛾卵(U)、新鲜杀胚米蛾卵(CK)、杀胚米蛾卵在4℃条件下冷藏15 d(N15)、30 d(N30)、45 d(N45)和60 d(N60)后,米蛾卵卵液游离氨基酸种类和含量的变化。结果共鉴定到24种游离氨基酸及其衍生物,包括昆虫发育必需的10种氨基酸。U和CK之间的游离氨基酸组分没有显著差异,N15、N30和N45游离氨基酸总量随冷藏时间的延长而显著升高,N60中的氨基酸总量与N45比较没有显著增加。对24种游离氨基酸及其衍生物的含量进行主成分分析,结果表明丙氨酸、谷氨酰胺、鸟氨酸、天冬氨酸、组氨酸、赖氨酸、丝氨酸、焦谷氨酸等8种氨基酸的含量随冷藏时间的增加而有着显著的变化,其中,丙氨酸变化幅度最为明显,随着冷藏时间的增加,含量从0.1624 mmol/L增加到8.6192 mmol/L;组氨酸在N30、N45和N60处理之间显著下降,从0.7553 mmol/L降低到0.2495 mmol/L。因此,冷藏会导致米蛾卵内游离氨基酸含量发生一定变化,这可能是冷藏米蛾卵影响赤眼蜂生长发育的重要原因之一。     

Pyruvate carboxylase: isolation of the biotin-containing tryptic peptide and the determination of its primary sequency

The biotin-containing tryptic peptides of pyruvate carboxylase from sheep, chicken, and turkey liver mitochondria have been isolated and their primary structures determined. The amino acid sequences of the 19 residue peptides from chicken and turkey are identical and share a common sequence of 14 residues around biocytin with the 24-residue peptide isolated from sheep. The sequences obtained were: residue 1 → 11 Avian: Gly Ala Pro Leu Val Leu Ser Ala Met Biocytin Met Sheep: Gly Gln Pro Leu Val Leu Ser Ala Met Biocytin Met residues 12 → 19 or 24 Avian: Glu Thr Val Val Thr Ala Pro Arg Sheep: Glu Thr Val Val Thr Ser Pro Val Thr Glu Gly Val Arg A sensitive radiochemical assay for biotin was developed based on the tight binding of biotin by avidin. The ability of zinc sulfate to precipitate, without dissociating, the avidin-biotin complex provided a convenient procedure for separating free and bound biotin, and hence, for back-titrating a standard amount of avidin with [¹⁴C]biotin.     

The amino acid sequence of human chorionic gonadotropin. The alpha subunit and beta subunit.

The amino acid sequences of both the alpha and beta subunits of human chorionic gonadotropin have been determined. The amino acid sequence of the alpha subunit is: Ala - Asp - Val - Gln - Asp - Cys - Pro - Glu - Cys-10 - Thr - Leu - Gln - Asp - Pro - Phe - Ser - Gln-20 - Pro - Gly - Ala - Pro - Ile - Leu - Gln - Cys - Met - Gly-30 - Cys - Cys - Phe - Ser - Arg - Ala - Tyr - Pro - Thr - Pro-40 - Leu - Arg - Ser - Lys - Lys - Thr - Met - Leu - Val - Gln-50 - Lys - Asn - Val - Thr - Ser - Glu - Ser - Thr - Cys - Cys-60 - Val - Ala - Lys - Ser - Thr - Asn - Arg - Val - Thr - Val-70 - Met - Gly - Gly - Phe - Lys - Val - Glu - Asn - His - Thr-80 - Ala - Cys - His - Cys - Ser - Thr - Cys - Tyr - Tyr - His-90 - Lys - Ser. Oligosaccharide side chains are attached at residues 52 and 78. In the preparations studied approximately 10 and 30% of the chains lack the initial 2 and 3 NH2-terminal residues, respectively. This sequence is almost identical with that of human luteinizing hormone (Sairam, M. R., Papkoff, H., and Li, C. H. (1972) Biochem. Biophys. Res. Commun. 48, 530-537). The amino acid sequence of the beta subunit is: Ser - Lys - Glu - Pro - Leu - Arg - Pro - Arg - Cys - Arg-10 - Pro - Ile - Asn - Ala - Thr - Leu - Ala - Val - Glu - Lys-20 - Glu - Gly - Cys - Pro - Val - Cys - Ile - Thr - Val - Asn-30 - Thr - Thr - Ile - Cys - Ala - Gly - Tyr - Cys - Pro - Thr-40 - Met - Thr - Arg - Val - Leu - Gln - Gly - Val - Leu - Pro-50 - Ala - Leu - Pro - Gin - Val - Val - Cys - Asn - Tyr - Arg-60 - Asp - Val - Arg - Phe - Glu - Ser - Ile - Arg - Leu - Pro-70 - Gly - Cys - Pro - Arg - Gly - Val - Asn - Pro - Val - Val-80 - Ser - Tyr - Ala - Val - Ala - Leu - Ser - Cys - Gln - Cys-90 - Ala - Leu - Cys - Arg - Arg - Ser - Thr - Thr - Asp - Cys-100 - Gly - Gly - Pro - Lys - Asp - His - Pro - Leu - Thr - Cys-110 - Asp - Asp - Pro - Arg - Phe - Gln - Asp - Ser - Ser - Ser - Ser - Lys - Ala - Pro - Pro - Pro - Ser - Leu - Pro - Ser-130 - Pro - Ser - Arg - Leu - Pro - Gly - Pro - Ser - Asp - Thr-140 - Pro - Ile - Leu - Pro - Gln. Oligosaccharide side chains are found at residues 13, 30, 121, 127, 132, and 138. The proteolytic enzyme, thrombin, which appears to cleave a limited number of arginyl bonds, proved helpful in the determination of the beta sequence.     

The primary structure of the β-subunit of protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa

The complete amino acid sequence of the β-subunit of protocatechuate 3,4-dioxygenase was determined. The β-subunit contained four methionine residues. Thus, five peptides were obtained after cleavage of the carboxymethylated β-subunit with cyanogen bromide, and were isolated on Sephadex G-75 column chromatography. The amino acid sequences of the cyanogen bromide peptides were established by characterization of the peptides obtained after digestion with trypsin, chymotrypsin, thermolysin, or Staphylococcus aureus protease. The major sequencing techniques used were automated and manual Edman degradations. The five cyanogen bromide peptides were aligned by means of the amino acid sequences of the peptides containing methionine purified from the tryptic hydrolysate of the carboxymethylated β-subunit. The amino acid sequence of all the 238 residues was as follows: ProAlaGlnAspAsnSerArgPheValIleArgAsp ArgAsnTrpHis ProLysAlaLeuThrPro-Asp — TyrLysThrSerIleAlaArg SerProArgGlnAla LeuValSerIleProGlnSer — IleSerGluThrThrGly ProAsnPheSerHisLeu GlyPheGlyAlaHisAsp-His — AspLeuLeuLeuAsnPheAsn AsnGlyGlyLeu ProIleGlyGluArgIle-Ile — ValAlaGlyArgValValAsp GlnTyrGlyLysPro ValProAsnThrLeuValGluMet — TrpGlnAlaAsnAla GlyGlyArgTyrArg HisLysAsnAspArgTyrLeuAlaPro — LeuAspProAsn PheGlyGlyValGly ArgCysLeuThrAspSerAspGlyTyrTyr — SerPheArg ThrIleLysProGlyPro TyrProTrpArgAsnGlyProAsnAsp — TrpArgProAla HisIleHisPheGlyIle SerGlyProSerIleAlaThr-Lys — LeuIleThrGlnLeuTyr PheGluGlyAspPro LeuIleProMetCysProIleVal — LysSerIleAlaAsn ProGluAlaValGlnGln LeuIleAlaLysLeuAspMetAsnAsn — AlaAsnProMet AsnCysLeuAlaTyr ArgPheAspIleValLeuArgGlyGlnArgLysThrHis PheGluAsnCys. The sequence published earlier in summary form (Iwaki et al., 1979, J. Biochem.86, 1159–1162) contained a few errors which are pointed out in this paper.     

Sequences of tryptic peptides containing the five cysteinyl residues of ribulosebisphosphate carboxylase/oxygenase from Rhodospirillum rubrum

Tryptic peptides which account for all five cysteinyl residues in ribulosebisphosphate carboxylase/oxygenase from Rhodospirillum rubrum have been purified and sequenced. Collectively, these peptides contain 94 of the approximately 500 amino acid residues per molecule of subunit. Due to one incomplete cleavage at a site for trypsin and two incomplete chymotryptic-like cleavages, eight major radioactive peptides (rather than five as predicted) were recovered from tryptic digests of the enzyme that had been carboxymethylated with [³H]iodoacetate. The established sequences are: GlyTyrThrAlaPheValHisCys¹Lys TyrValAspLeuAlaLeuLysGluGluAspLeuIleAla GlyGlyGluHisValLeuCys¹AlaTyr AlaGlyTyrGlyTyrValAlaThrAlaAlaHisPheAla AlaGluSerSerThrGlyThrAspValGluValCys¹ ThrThrAsxAsxPheThrArg AlaCys¹ThrProIleIleSerGlyGlyMetAsnAla LeuArg ProPheAlaGluAlaCys¹HisAlaPheTrpLeuGly GlyAsnPheIleLys In these peptides, radioactive carboxymethylcysteinyl residues are denoted with asterisks and the sites of incomplete cleavage with vertical wavy lines. None of the peptides appear homologous with either of two cysteinyl-containing, active-site peptides previously isolated from spinach ribulosebisphosphate carboxylase/oxygenase.     

Amino acid sequence of a protease inhibitor isolated from Sarcophaga bullata determined by mass spectrometry.

The amino acid sequence of a protease inhibitor isolated from the hemolymph of Sarcophaga bullata larvae was determined by tandem mass spectrometry. Homology considerations with respect to other protease inhibitors with known primary structures assisted in the choice of the procedure followed in the sequence determination and in the alignment of the various peptides obtained from specific chemical cleavage at cysteines and enzyme digests of the S. bullata protease inhibitor. The resulting sequence of 57 residues is as follows: Val Asp Lys Ser Ala Cys Leu Gln Pro Lys Glu Val Gly Pro Cys Arg Lys Ser Asp Phe Val Phe Phe Tyr Asn Ala Asp Thr Lys Ala Cys Glu Glu Phe Leu Tyr Gly Gly Cys Arg Gly Asn Asp Asn Arg Phe Asn Thr Lys Glu Glu Cys Glu Lys Leu Cys Leu.     

Deracemization of Amino Acids by Partial Sublimation and via Homochiral Self-Organization

Deracemization of a 50/50 mixture of enantiomers of aliphatic amino acids (Ala, Leu, Pro, Val) can be achieved by a simple sublimation of a pre-solubilized solid mixture of the racemates with a huge amount of a less-volatile optically active amino acid (Asn, Asp, Glu, Ser, Thr). The choice of chirality correlates with the handedness of the enantiopure amino acids—Asn, Asp, Glu, Ser, and Thr. The deracemization, enantioenrichment and enantiodepletion observed in these experiments clearly demonstrate the preferential homochiral interactions and a tendency of natural amino acids to homochiral self-organization. These data may contribute toward an ultimate understanding of the pathways by which prebiological homochirality might have emerged.     

甘肃鼢鼠骨骼19种氨基酸含量的测定

用121型氨基酸分析仪对甘肃鼢鼠(Myospalax cansus)躯干、四肢、头骨骨骼中19种氨基酸含量进行测定,并与高原鼢鼠及其他哺乳动物骨骼中氨基酸含量进行差异显著性分析。结果表明,甘肃鼢鼠各部位骨骼中19种氨基酸含量均为甘氨酸最高,谷氨酸次之,胱氨酸最低。同一氨基酸在甘肃鼢鼠不同骨骼部位含量顺序为躯干>四肢(头骨。甘肃鼢鼠骨骼总氨基酸含量低于塞隆骨,与虎骨相近,高于其他哺乳动物。其中羟脯氨酸含量明显高于虎骨、塞隆骨等。     

Effects of orally administrated amino acids on myofibrillar proteolysis in chicks

We examined the effects of orally administrated amino acids on myfibrillar proteolysis in food-deprived chicks. Plasma N(tau)-methylhistidine concentration, as an index of myofibrillar proteolysis, was decreased by the administration of Glu, Gly, Ala, Leu, Ile, Ser, Thr, Met, Trp, Asn, Gln, Pro, Lys and Arg but not by Asp, Val, Phe, Tyr or His to chicks. Orally administrated Cys was fatal to chicks. These results indicate that oral Glu, Gly, Ala, Leu, Ile, Ser, Thr, Met, Trp, Asn, Gln, Pro, Lys and Arg administration suppressed myofibrillar proteolysis in chicks.     

Significance of Extracellular Protease for Growth of a Heterotrophic Bacterium, Aeromonas salmonicida

The role of protease produced by a heterotrophic bacterium during growth was investigated with Aeromonas salmonicida, the pathogen of fish furunculosis, strain A-7301 and its protease-deficient mutant NTG-1 induced by mutagenesis. Strain A-7301 produced extracellular protease in a mixed amino acid medium (composed of Gly, Ala, Val, Ile, Leu, Thr, Ser, Cys, Met, Phe, Tyr, Lys, Arg, Pro, His, Try, Asp, Asn, Glu, and Gln at equal concentrations of 0.1 g/liter). Its multiplication rate was limited by the amounts of amino acids present, whereas strain NTG-1 showed no protease production despite considerable growth similar to that of A-7301. There was no difference between A-7301 and NTG-1 in amino acid requirements for growth, and seven amino acids (Gly, Ala, Val, Thr, Cys, Met, and His) were found to be indispensable. A defined level of the mixed amino acids (0.4 to 0.5 g/liter) was needed for A-7301 to initiate a large production of protease. Neither of the strains grew well in a casein medium, to which no amino acids were added. However, when a protease fraction obtained from extracellular products of A-7301 by DEAE-cellulose column chromatography was added, NTG-1 successfully reproduced in the casein medium. These results indicate that the extracellular protease plays an important role in supplying A. salmonicida cells with available amino acids as nutrients and that higher growth is closely associated with protease production which stimulates further reproduction.     

Engineering of papain: selective alteration of substrate specificity by site-directed mutagenesis

The S2 subsite specificity of the plant protease papain has been altered to resemble that of mammalian cathepsin B by site-directed mutagenesis. On the basis of amino acid sequence alignments for papain and cathepsin B, a double mutant (Val133Ala/Ser205Glu) was produced where Val133 and Ser205 are replaced by Ala and Glu, respectively, as well as a triple mutant (Val133Ala/Val157Gly/Ser205Glu), where Val157 is also replaced by Gly. Three synthetic substrates were used for the kinetic characterization of the mutants, as well as wild-type papain and cathepsin B: CBZ-Phe-Arg-MCA, CBZ-Arg-Arg-MCA, and CBZ-Cit-Arg-MCA. The ratio of kcat/KM obtained by using CBZ-Phe-Arg-MCA as substrate over that obtained with CBZ-Arg-Arg-MCA is 8.0 for the Val133Ala/Ser205Glu variant, while the equivalent values for wild-type papain and cathepsin B are 904 and 3.6, respectively. This change in specificity has been achieved by replacing only two amino acids out of a total of 212 in papain and with little loss in overall enzyme activity. However, further replacement of Val157 by Gly as in Val133Ala/Val157Gly/Ser205Glu causes an important decrease in activity, although the enzyme still displays a cathepsin B like substrate specificity. In addition, the pH dependence of activity for the Val133Ala/Ser205Glu variant compares well with that of cathepsin B. In particular, the activity toward CBZ-Arg-Arg-MCA is modulated by a group with a pKa of 5.51, a behavior that is also encountered in the case of cathepsin B but is absent with papain.(ABSTRACT TRUNCATED AT 250 WORDS)