Preparation of α-aminothioamides from aldehydes

1987 ◽  
Vol 65 (2) ◽  
pp. 282-289 ◽  
Author(s):  
Martino Paventi ◽  
John T. Edward
Keyword(s):  
Amino Acids ◽  
Naturally Occurring ◽  
Hydrolysis Of

The conversion of aldehydes into α-aminonitriles and thence into imidazolidin-4-thiones has been studied. Hydrolysis of the appropriate imidazolidin-4-thiones gave thioamides of nine naturally occurring α-amino acids. The possible pre-biotic significance of these compounds is discussed.

Deinking of recycled paper by coupling of the enzyme endo-β-1,4-D-glucanasa and the cellulose, and by using a laboratory flotation column

MRS Advances ◽  
2020 ◽  
Vol 5 (52-53) ◽  
pp. 2669-2678
Author(s):  
Jeovani González P. ◽  
Ramiro Escudero G
Keyword(s):  
Amino Acids ◽  
Sodium Hydroxide ◽  
Paper Industry ◽  
Computational Simulation ◽  
Cellulose Fibers ◽  
Residual Water ◽  
Chemical Reagent ◽  
Recycled Paper ◽  
Flotation Column ◽  
Hydrolysis Of

AbstractDeinking of recycled office (MOW) paper was carried out by using a flotation column and adding separately sodium hydroxide, and the enzyme Cellulase Thricodema Sp., as defibrillators.The de-inked cellulose fibers were characterized according to the standards of the paper industry, to compare the efficiency of the deinking of each chemical reagent used to hydrolyze the fibers and defibrillate them.The computational simulation of the molecular coupling between the enzyme and cellulose was performed, to establish the enzyme-cellulose molecular complex and then to identify the principal amino-acids of endo-β-1,4-D-glucanase in this molecular link, which are responsible for the hydrolysis of the cellulose.Experimental results show the feasibility to replace sodium hydroxide with the enzyme Cellulase Thricodema Sp., by obtaining deinked cellulose with similar optical and physical properties.The use of the enzyme instead of sodium hydroxide avoids the contamination of the residual water; in addition to that, the column is operated more easily, taking into consideration that the pH of the system goes from alkaline to neutral.

Studies on Chromatographic Fractioning by Cations Exchangers of a Bovine Hemoglobin Hydrolysate

2018 ◽  
Vol 69 (10) ◽  
pp. 2794-2798
Author(s):  
Alina Diana Panainte ◽  
Ionela Daniela Morariu ◽  
Nela Bibire ◽  
Madalina Vieriu ◽  
Gladiola Tantaru ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Retention Time ◽  
Chromatographic Separation ◽  
Bovine Hemoglobin ◽  
Reverse Phase ◽  
Hplc System ◽  
Fast Flow ◽  
Hydrolysis Of ◽  
Phase Column

A peptidic hydrolysate has been obtained through hydrolysis of bovine hemoglobin using pepsin. The fractioning of the hydrolysate was performed on a column packed with CM-Sepharose Fast Flow. The hydrolysate and each fraction was filtered and then injected into a HPLC system equipped with a Vydak C4 reverse phase column (0.46 x 25 cm), suitable for the chromatographic separation of large peptides with 20 to 30 amino acids. The detection was done using mass spectrometry, and the retention time, size and distribution of the peptides were determined.

scholarly journals The α-Chymotrypsin-catalyzed Hydrolysis of Esters of α-Amino Acids

1972 ◽  
Vol 247 (18) ◽  
pp. 5746-5752
Author(s):  
Ferenc J. Kézdy ◽  
Satya P. Jindal ◽  
Myron L. Bender
Keyword(s):  
Amino Acids ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

Variation in Quantity of Methanol Recovered from Raisins

1963 ◽  
Vol 46 (2) ◽  
pp. 341-343
Author(s):  
M Alice Brown ◽  
James R Woodward ◽  
Floyd DeEds
Keyword(s):  
Methyl Ester ◽  
Esterase Activity ◽  
Enzymic Hydrolysis ◽  
Methanol Content ◽  
Naturally Occurring ◽  
Pectin Esterase ◽  
Hydrolysis Of

Abstract The amount of naturally occurring methanol in fruit must be known so that the quantity left as fumigation residue can be determined. In a study of methanol content of raisins, which had given inconsistent results, the raisins were subjected to different conditions of treatment immediately prior to methanol determination. Conditions that favored pectin esterase activity gave higher values for methanol content than conditions known to inactivate enzymes. Evidence was also obtained that both chemical and enzymic hydrolysis of methyl ester groups of pectic materials occur during analysis.

Availability of amino acids supplied by constant intravenous infusion of synthetic dipeptides in healthy man

1989 ◽  
Vol 76 (6) ◽  
pp. 643-648 ◽  
Author(s):  
S. Albers ◽  
J. Wernerman ◽  
P. Stehle ◽  
E. Vinnars ◽  
P. Fürst
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Metabolic Clearance ◽  
Amino Acid Solution ◽  
Appreciable Change ◽  
Total Body ◽  
Hydrolysis Of ◽  
Firm Evidence ◽  
Apparently Healthy

1. A commercial amino acid solution supplemented with two synthetic dipeptides, l-alanyl-l-glutamine (Ala-Gln) and glycyl-l-tyrosine (Gly-Tyr), or alternatively with isonitrogenous amounts of free alanine and glycine has been continuously infused over 4 h in six apparently healthy volunteers. 2. The infusion of the solutions was not accompanied by any side effects and the volunteers reported no complaints. 3. Infusion of the alanine- and glycine-supplemented control solution resulted in an increase of the concentration of these amino acids, while no appreciable change in free glutamine concentration was observed and free tyrosine revealed a steady decrease throughout the infusion. 4. Infusion of the peptide-supplemented solution resulted in a prompt equimolar liberation of the constituent free amino acids (glutamine, alanine, tyrosine and glycine), approaching steady state after about 30 min infusion, while only trace but stable concentrations of the two dipeptides were measured throughout the infusion. No peptides were detectable in urine. The findings suggest a nearly quantitative extracellular hydrolysis of the infused dipeptides and indicate a subsequent utilization of the liberated free amino acids. 5. The estimated metabolic clearance rates and total body plasma clearances were very similar for the two dipeptides (Ala-Gln 35.9 ± 9.5 ml min−1 kg−1 and 2.9 ± 0.9 1/min, respectively; Gly-Tyr 33.7 ± 9.5 ml min−1 kg−1 and 2.7 ± 0.9 1/min, respectively); thus there is little difference in the metabolic handling of these dipeptides. 6. The study provides firm evidence that the synthetic dipeptides Ala-Gln and Gly-Tyr are quantitatively hydrolysed and that these peptides can be used as a safe and efficient source of free glutamine and tyrosine as part of a commercial solution.

Covalent attachment of amino acids to casein. 1. Chemical modification and rates of in vitro enzymic hydrolysis of derivatives

1979 ◽  
Vol 27 (5) ◽  
pp. 1098-1104 ◽  
Author(s):  
Antoine J. Puigserver ◽  
Lourminia C. Sen ◽  
Elvira Gonzales-Flores ◽  
Robert E. Feeney ◽  
John R. Whitaker
Keyword(s):  
Amino Acids ◽  
Chemical Modification ◽  
Covalent Attachment ◽  
Enzymic Hydrolysis ◽  
Hydrolysis Of

scholarly journals Regulation of rat magnocellular neurosecretory system by D-aspartate: evidence for biological role(s) of a naturally occurring free D-amino acid in mammals

2000 ◽  
Vol 167 (2) ◽  
pp. 247-252 ◽  
Author(s):  
H Wang ◽  
H Wolosker ◽  
J Pevsner ◽  
SH Snyder ◽  
DJ Selkoe
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Amino Acid ◽  
Physiological Function ◽  
Neurosecretory System ◽  
Milk Ejection ◽  
Magnocellular Neurons ◽  
Rat Hypothalamus ◽  
Naturally Occurring

Little evidence is available for the physiological function of D-amino acids in species other than bacteria. Here we demonstrate that naturally occurring freed -aspartate (D-Asp) is present in all magnocellular neurons of rat hypothalamus. The levels of this naturally occurring D-amino acid were elevated during lactation and returned to normal thereafter in the magnocellular neurosecretory system, which produces oxytocin, a hormone responsible for milk ejection during lactation. Intraperitoneal injections of D-Asp reproducibly increased oxytocin gene expression and decreased the concentration of circulating oxytocin in vivo. Similar changes were observed in the vasopressin system. These results provide evidence for the role(s) of naturally occurring free D-Asp in mammalian physiology. The findings argue against the conventional concept that only L-stereoisomers of amino acids are functional in higher species.

scholarly journals Isolation, purification and structure of exochelin MS, the extracellular siderophore from Mycobacterium smegmatis

1995 ◽  
Vol 305 (1) ◽  
pp. 187-196 ◽  
Author(s):  
G J Sharman ◽  
D H Williams ◽  
D F Ewing ◽  
C Ratledge
Keyword(s):  
Amino Acids ◽  
Mycobacterium Smegmatis ◽  
Methyl Esters ◽  
Three Dimensional ◽  
Iron Chelation ◽  
Peptide Bond ◽  
Exchange Chromatography ◽  
Peptide Bonds ◽  
Hydrolysis Of ◽  
Gallium Complex

The extracellular siderophore from Mycobacterium smegmatis, exochelin MS, was isolated from iron-deficiently grown cultures and purified to > 98% by a combination of ion-exchange chromatography and h.p.l.c. The material is unextractable into organic solvents, is basic (pI = 9.3-9.5), has a lambda max at 420 nm and a probable Ks for Fe3+ of between 10(25) and 10(30). Its structure has been determined by examination of desferri- and ferri-exochelin and its gallium complex. The methods used were electrospray-m.s. and one- and two-dimensional (NOESY, DQF-COSY and TOCSY) 1H n.m.r. The constituent amino acids were examined by chiral g.l.c analysis of N-trifluoroacetyl isopropyl and N-pentafluoropropionyl methyl esters after hydrolysis, and reductive HI hydrolysis, of the siderophore. The exochelin is a formylated pentapeptide: N-(delta-N-formyl,delta N-hydroxy-R-ornithyl) -beta-alaninyl-delta N-hydroxy-R-ornithinyl-R-allo-threoninyl-delta N-hydroxy-S-ornithine. The linkages involving the three ornithine residues are via their delta N(OH) and alpha-CO groups leaving three free alpha-NH2 groups. Although there are two peptide bonds, these involve the three R (D)-amino acids. Thus the molecule has no conventional peptide bond, and this suggests that it will be resistant to peptidase hydrolysis. The co-ordination centre with Fe3+ is hexadenate in an octahedral structure involving the three hydroxamic acid groups. Molecular modelling shows it to have similar features to other ferric trihydroxamate siderophores whose three-dimensional structures have been established. The molecule is shown to have little flexibility around the iron chelation centre, although the terminal (Orn-3) residue, which is not involved in iron binding except at its delta N atom, has more motional freedom.

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