Hydrolysis of N-phenylacetyl-α-methyl-α-amino acids by benzylpenicillinacylase

Summary Enzymatic hydrolysis of several racemic N-phenylacetyl--methyl--amino acids containing an additinal aliphatic, aromatic or polar substitutent on the chiral carbon atom, has been studied by using benzylpenicillincylase fromEscherichia coli A.T.C.C. 9637. Both the rate of hydrolysis and the stereoselectivity were found to be considerably lower than in the case of natural -amino acids. Steric and electronic factors in the side chains influencing the stereoselectivity are discussed.     

Free amino acid pattern in stressed leaves of two contrasting resistant and susceptible cultivars of chick pea (Cicer arietinum)

Summary Drought resistant cv. C-214 ofCicer arietinum L. showed higher accumulation of alanine, threonine, glutamine, -alanine, arginine, amino butyric acid, valine, leucine, phenylalanine than the susceptible cv. G130 under water stress.     

PW12/MCM-41上异丁烷/丁烯烷基化反应

采用水热法制备负载型PW12/MCM-41催化剂,用XRD、IR、TG-DTA表征催化剂的结构、杂多酸的分散性及酸性.结果表明:PW12/MCM-41催化剂具有强酸性;在负载量高达40%的催化剂上,磷钨酸保持着Keggin结构.负载40%PW12的催化剂用于异丁烷与丁烯的烷基化,该催化剂的酸性受活化温度影响,最佳温度为250 ℃.超临界态下反应明显延长了催化剂寿命,但是液相产物中烯烃含量仍然很高.     

用有机溶剂抽提直馏柴油中的环烷酸

采用有机溶剂抽提法脱除柴油中的环烷酸，并运用表现分配比概念，考察了环烷酸这种混合物在95％乙醇和柴油中的表观分配比，环烷酸在95％乙醇和柴油两相间的表观分配比为2.0±0．2这是一个较恒定的数值。以此数值对抽提结果进行推测，其推测值与实验测定值吻合得很好．对抽提所应采用的工艺条件进行了室内研究，结果表明，95％乙醇为抽提环烷酸的优良溶剂，经抽提可脱除柴油中80％以上的环烷酸，精制后的柴油的酸值合格，安定性有明显提高．溶剂可回收利用，不污染环境．     

Free intracellular and protein bound amino acids in tissues as affected by a mixedβ-adrenergic agonist

The administration of metaproterenol induced an increase in gastrocnemius muscle weight without change in body growth rate or tissue protein concentrations, while epididymal fat was reduced. This effect was accompanied by an enhancement in the levels of intracellular amino acids in muscle. By contrast, liver amino acids were unaffected by treatment with the mixed -adrenergic agonist.     

ω10-Lipoxygenase products of α-linolenic acid are esterified to phospholipids inHydra vulgaris

We have recently reported the occurrence of 9(R)-hydroxy-, 9(R)-hydroperoxy- and 9-keto-octadeca-10E,12Z,15Z-trienoic acids (9-HOTrE, 9-HPOTrE and 9-KOTrE) inHydra vulgaris, and their biosynthesis from -linolenic acid (-LA) through the action of an enantioselective 10(R)-lipoxygenase (10-LO). Here we describe the finding of these -LA metabolites as esters to the 2-position of phosphatidylcholine, phosphatidylethanolamine and, in trace amounts, phosphatidylinositol. Small amounts of a compound co-eluting with an authentic standard of 9(R)-hydroxy-octadeca-10E,12Z-dienoic acid, a metabolite potentially derived from the action of 10-LO on linoleic acid, were also found esterified with phospholipids. Since direct peroxidation of membrane lipids has been described, experiments were aimed at establishing whether -LA metabolite-containing phospholipids could originate, inH. vulgaris, from either spontaneous or 10-LO-catalyzed oxidation of phospholipid-bound -LA. Incubation of either unlabelled or radiolabelled PUFA-containing phosphoglycerides withH. vulgaris 10-LO did not result in their peroxidation. This suggests that -LA and LA metabolites are incorporated into glycerophospholipids after their formation by 10-LO, and that, as in mamals, membrane phospholipids may serve as a reservoir for these bioactive compounds. This is the first example in an invertebrate species of lipoxygenase products esterified to phosphoglycerides.     

深黄被孢霉及其脂溶性组分对高脂饮食小鼠的影响

研究深黄被孢霉菌粉及其脂溶性组分对脂代谢紊乱小鼠的调节作用．小鼠膳食高脂饲料13周后建模成功，随后以菌粉及其提取物继续喂食7周．实验结果证明菌粉治疗作用的靶位点之一是白色脂肪组织，可引起小鼠体质量显著性下降；菌粉及其提取物能降低高脂饮食小鼠的TC／HDL-c的水平，改善血浆胆固醇比例．     

泡沫浮选萃取分离回收废水中铜锌

在内循环浮选柱中,采用泡沫浮选萃取法对模拟废水中的铜锌离子进行了分离回收实验,研究了废水pH值、浮选时间、气速、环烷酸浓度等对分离效果的影响.结果表明,利用皂化环烷酸作为浮选萃取剂,两段浮选萃取,第一阶段在pH=2.7时优先浮选萃取铜,回收率达95%,而锌的回收率约为10%;然后在第二阶段升高残液pH值至7.9浮选萃取锌,可完全除去锌离子,残留废水达到排放标准.确定了泡沫浮选萃取分离回收铜锌的工艺路线,并制得工业纯硫酸铜和硫酸锌产物.     

腐殖酸除锰及利用微滤膜分析有机锰质量分数

研究了水中腐殖酸对接触氧化法除锰效果的影响，并利用微滤膜污染机理分析了水中有机锰的质量分数．由实验可知，水中腐殖酸会影响除锰效果，影响程度随着腐殖酸质量浓度的提高而增大；锰与腐殖酸络合形成的有机锰易吸附于膜表面而被醋酸质微滤膜所截留，膜通量随过滤次数的变化特征表明，水中有机锰经3次重复过滤后，有机锰基本全被吸附．在锰离子质量浓度为1mg/L左右的条件下，当腐殖酸质量浓度为8mg/L时，吸附的有机锰量是水中锰离子量的23％，当腐殖酸质量浓度为20mg/L时为33．5％，该数值与采用截留分子质量为3000的超滤膜得出的结果23．8％和35％基本吻合，可以利用这个机理快捷定量地分析水中有机锰的质量分数。     

差示扫描量热法确定5种氨基酸的热动力学参数

用差动热分析仪测得Gly、Ala、Val、Leu和Ile的DSC曲线，采用普适积分法和微分方程法通过逻辑选择确定了它们热动力学过程的最可几机理函数F(α)=[-ln(1-α)]^4，f(a)=(1／4)(1-α)[-ln(1-α)]^-3，并计算出相应的热动力学参数，发现热动力学参数随着R基的供电子效应的增强而降低．