STUDIES ON ENZYME ACTION : XXXVIII. THE ESTER-HYDROLYZING ACTIONS OF THE WHOLE EEL.

The hydrolyzing actions of various preparations of the adult eel were studied on ten esters in the usual way. The results are presented in the form of curves for the relative actions and in a table for the absolute actions obtained in one complete experiment. The separation of the enzyme material in some cases into an active portion and a co-enzyme, the mixture showing greater actions on some esters than the sums of the individual actions, is described and discussed.     

STUDIES ON ENZYME ACTION : XLV. LIPASE ACTIONS OF THE WHOLE TROUT AT DIFFERENT AGES.

The ester-hydrolyzing or lipase actions of extracts and whole solids of trout eggs and whole trout of different ages were tested on ten simple esters by the method described in previous papers. Differences in solubility of the enzyme materials of the eggs were found. The "pictures" of the relative enzyme actions changed from a type found with immature eggs to a type which became constant for the fish after they had eaten for 2 weeks. After this, the type did not change up to the age of 4 to 5 years (the oldest trout studied). The absolute ester-hydrolyzing actions of the materials were also presented and discussed.     

STUDIES ON ENZYME ACTION : XXXIII. LIPASE ACTIONS OF EXTRACTS OF THE WHOLE RAT AT DIFFERENT AGES.

The ester-hydrolyzing or lipase actions of extracts of whole rats whose ages ranged from 3 days before birth to 3 years 15 days were tested on ten simple esters by the method described in previous papers. The results are presented in the form of curves, both as absolute actions and as relative actions on the different substrates. The "pictures" of the relative actions changed progressively with increasing age of the rat. For the embryo and the youngest rats, the curves approached those given by the Flexner-Jobling rat carcinoma and by a number of tumors of human origin, changing to a type characteristic of the adult rat, and appearing to revert again to some extent to the embryonic type for the oldest rats. The changes in the actions on individual esters and the relative changes in the actions on different esters are discussed in detail. The greatest increases in actions as the rats became older were found with methyl and ethyl butyrates; at the same time that the actions on some of the other esters were also found to change in characteristic ways. Similar experiments with the protease actions of the extracts of whole rats of different ages on three protein preparations did not give differences similar to those found for the lipase actions. The probable reasons for these observed differences in the two sets of enzyme actions are discussed.     

STUDIES ON ENZYME ACTION : XXXIX. LIPASE ACTIONS OF EXTRACTS OF THE WHOLE MOUSE AT DIFFERENT AGES.

The ester-hydrolyzing or lipase actions of extracts of whole mice whose ages ranged from approximately 6 days before birth to 1 year 8 months 21 days were tested on ten simple esters by the method described in previous papers. The "pictures" of the relative enzyme actions changed from a type approaching the "embryonic" as found with embryo rats and a number of tissues of rabbit embryo, to a type characteristic of the adult mouse. The mouse embryos corresponded to the rat embryos in type and differed markedly from the mouse carcinomas which have been studied. The relative and absolute enzyme actions are discussed in some detail, and the results compared with the results obtained for the life cycle of the rat.     

STUDIES ON ENZYME ACTION : XIX. THE SUCROLYTIC ACTIONS OF BANANAS.

A number of different methods of treatment of unripe and ripe bananas for the purpose of obtaining and studying sucrolytic and amylolytic enzymes are described. No conclusive evidence of the presence of an amlyase could be obtained in any of the preparations. The sucrase of unripe and ripe bananas was studied more extensively. With ripe bananas, both soluble and insoluble sucrase preparations were obtained. Conditions for converting the soluble into an insoluble form were found. The actions of the sucrase preparations as far as the hydrogen ion concentration for maximum action and the time-action relation are concerned are similar to the behavior of the yeast and the potato sucrase.     

STUDIES ON ENZYME ACTION : XVIII. THE SACCHAROGENIC ACTIONS OF POTATO JUICE.

The saccharogenic enzymes present in potato juice were studied. The actions were followed upon the substances present in the juice and upon added sucrose, maltose, and soluble starch. Sucrase and amylase were found to be present in the juice. No indication of a maltase was obtained. The sucrase showed optimum conditions for action at pH 4 to 5, the amylase at pH 6 to 7, both upon the starch present in the juice and upon added soluble starch. The action of a yeast sucrase preparation upon the juice showed the presence of sucrose (or raffinose) in a concentration of the order of magnitude of 1 per cent.     

STUDIES ON ENZYME ACTION : XXXV. LIPASE ACTIONS OF EXTRACTS OF TISSUES OF RABBITS AT DIFFERENT AGES.

The ester-hydrolyzing actions of extracts of a number of tissues of rabbits of different ages were studied under comparable conditions. The ages of the rabbits ranged from 8 days before birth to 2162 days. The esters used included phenyl acetate, glyceryl triacetate, methyl butyrate, benzyl acetate, methyl acetate, ethyl acetate, ethyl butyrate, methyl benzoate, ethyl benzoate, and isobutyl acetate. The following tissues were studied: kidney, liver, lung, skin, leg muscle, heart muscle, brain, spleen, stomach, and small intestine. The results, as in previous communications, are presented in the form of plots for the relative enzyme actions, and in tables for the absolute actions. The changes in the curves of the relative actions as the rabbits became older are considered in some detail. The relations between the embryonic state of certain tissues, as shown by their enzyme actions, and the adult state, are described, and compared with their physiological behavior. The probable reversion to a type approaching the embryonic for the oldest rabbits studied is indicated with some of the tissues. The changes in the absolute enzyme actions of the tissues as the rabbits became older are also discussed. The absolute actions do not form as regular a progression as do the relative actions but, at the same time, show marked regularities with increasing age of the rabbits.     

豆乳凝固醇产生菌UV—10发酵条件及其酶学性质的研究

豆乳凝固醇产生菌Bacillus sp.UV-10的最适产酶条件,初始pH6.4,温度26℃,培养时间19h,需要较大的通气量,酶的最适作用pH和温度分别为5．8和70℃,在最适条件下酶活力可达1.84u/mL,pH6.0-7.0稳定性较好,60℃下1h残余酶活60％,Ca^2 ,Fe^2 ,Mg^2 ,Na^2 对其有较强的激活作用,而Zn^2 ,Al^3 则有抑制作用。     

豆乳凝固酶产生菌UV-10发酵条件及其酶学性质的研究

豆乳凝固酶产生菌Bacillussp .UV 1 0的最适产酶条件 :初始pH6 4,温度 2 6℃ ,培养时间 1 9h ,需要较大的通气量。酶的最适作用pH和温度分别为 5 8和 70℃。在最适条件下酶活力可达 1 84u/mL。pH6 0～ 7 0稳定性较好。 6 0℃下 1h残余酶活 6 0 %。Ca²⁺,Fe²⁺,Mg²⁺,Na⁺对其有较强的激活作用 ,而Zn²⁺,Al相似文献   

ADSORPTION OF BACTERIOPHAGE UNDER VARIOUS PHYSIOLOGICAL CONDITIONS OF THE HOST

1. The adsorption rate constant of phage to bacterium is found to change between wide limits, depending on the physiological state of the bacterium. 2. The experiments of Krueger and of Schlesinger on the residual free phage in contact with an excess of bacteria are discussed and the view of Schlesinger, that they represent phage particles with reduced affinity to the bacterial host is supported by experiments. 3. The theory of von Smoluchowski and Schlesinger is compared with the experiments. 4. The implications of these findings for the assay methods currently used are discussed.     

EFFECT OF PRETREATMENT UNDER VARIOUS CATIONIC CONDITIONS ON ACETYLCHOLINE CONTENT AND CHOLINE TRANSPORT IN RAT WHOLE BRAIN SYNAPTOSOMES

The effects of different ionic environments were measured on the concentration of acetyl-choline (ACh) from synaptosomes and their effect on subsequent high affinity choline (Ch) transport and ACh synthesis after resuspension of the synaptosomes in the normal Krebs medium. KCl (40 mM) was used to induce ACh release and reduce synaptosomal ACh content. The effects of Na⁺ omission, Ca²⁺ omission, and high Mg²⁺ on spontaneous (KC1: 4.75 mM) and potassium induced (KC1: 40 mM) ACh release and other cholinergic parameters are presented. The high affinity transport of Ch was more highly correlated with the reciprocal of the ACh level (r= 0.934, P= 9.7 × 10^-4) than with the ACh release rate during preincubation (r= 0.792, P= 3.4 × 10^-2). The results are consistent with the view that the consequences of the various ionic conditions on Ch transport and ACh synthesis are dependent on their effects on intrasynaptosomal ACh levels and only secondarily on synaptosomal ACh release.     

不同条件下蛭弧菌裂解河流弧菌的研究

选择四种不同培养液,控制温度、pH和Ca＋＋Mg＋＋离子的不同水平,进行蛭弧菌HD94－12－7对河流弧菌WY91－24－3的裂解实验,结果表明,在灭菌蒸馏水、灭菌自来水、灭菌池塘水及Trisbuffer培养液中蛭弧菌HD94－12－7均表现出良好的裂解活性;温度在20—35℃时,蛭弧菌的裂解活性最大,低于15℃时,蛭弧菌的裂解能力明显减弱;pH值在6.5—8．1之间,蛭弧菌的裂解强度最大,pH低于5．6或高于8．1时,不利于蛭弧菌的生存。Ca＋＋,Mg＋＋离子能明显提高蛭弧菌的裂解活性。本研究证实了在实验条件下蛭弧菌对鱼类致病菌一河流弧菌具有明显地清除作用。     

相同条件下的5种甘草中甘草酸含量的比较研究

通过双波长薄层扫描对同一生长环境下生长时间相同的5种甘草进行了甘草酸含量的分析、比较,并首次分析了采收时间对甘草中甘草酸含量的影响。同时通过HPLC法对刺果甘草进行了甘草酸的定性分析。为甘草的质量评价、采收时间及种间鉴别提供了依据。     

STUDIES ON THE MECHANISM OF ACTION OF PEDERINE

Pederine, a drug extracted from the coleopter Paederus fuscipes, inhibits the growth of in vitro cultured cell lines at concentrations of the order of 1.5 nanogram/ml. Cytological examination shows a generalized cytotoxic effect. Analysis of macromolecular syntheses by the use of radioactive precursors shows that pederine causes an almost immediate block of protein and DNA synthesis, without affecting RNA synthesis. The effects on the synthesis of the two types of macromolecules remain nearly simultaneous even at the lowest active concentrations of pederine. Studies with cell-free systems show that the drug inhibits protein synthesis, whereas it is ineffective on the DNA-polymerizing activity. It seems, therefore, that the drug acts primarily on the amino acid-polymerizing system, and that the effect on DNA is secondary. This idea is strengthened by the observation that puromycin, a specific inhibitor of protein synthesis, also affects promptly DNA synthesis of in vitro cultured cells. Other authors have shown the same phenomenon with a number of inhibitors of protein synthesis; the properties of pederine support, therefore, the view that continuous protein synthesis is necessary for the maintenance of DNA replication in higher organisms.     

A STUDY OF THE BACTERICIDAL ACTION OF ULTRA VIOLET LIGHT : II. THE EFFECT OF VARIOUS ENVIRONMENTAL FACTORS AND CONDITIONS

1. Wide differences in the intensity of incident ultra violet energy are not accurately compensated by corresponding changes in the exposure time, so that the Bunsen-Roscoe reciprocity law does not hold, strictly, especially for bactericidal action on young, metabolically and genetically active bacteria. In the present series of experiments, however, the energies used at various wave lengths did not differ by so much as to cause a significant error in the reported reactions. 2. The longer wave length limit of a direct bactericidal action on S. aureus was found to be between 302 and 313 mµ. The shorter limit was not determined because the long exposures required vitiate quantitative results. Bactericidal action was observed at λ225 mµ. 3. The temperature coefficient of the bactericidal reaction approaches 1 and thus furnishes empirical evidence that the direct action of ultra violet light on bacteria is essentially physical or photochemical in character. 4. The hydrogen ion concentration of the environment has no appreciable effect upon the bactericidal reaction between the limits of pH 4.5 and 7.5. At pH 9 and 10 evidence of a slight but definite increase in bacterial susceptibility was noted, but this difference may have been due to a less favorable environment for subsequent recovery and multiplication of injured organisms. 5. Plane polarization of incident ultra violet radiation has no demonstrable effect upon its bactericidal action. In a third paper of this group the ratios of incident to absorbed ultra violet energy at various wave lengths and the significance of these relations in an analysis of the bactericidal reaction will be discussed.