PubMed Health⌕ Search

Biomedical subjects

C J Gray

Publications and source records attributed to C J Gray.

At least 19 recordsLinked to original sources
PubMed1996

Synthesis of azaalanine peptides using the solid phase method.

The methodology for the incorporation of azaamino-acid residues into peptides synthesised by a solid-phase method has been extended to allow azaalanine peptides to be prepared. In this way, Ac-Leu-Ser-Gly-azaAla-Gly-Phe-Ser-Leu-NH2 H-Ala-Ala-Lys-Glu-Ala-Ala-Glu-Ala -Ala-Glu-Lys-Ala-azaAla-Glu-Leu-Ala-Leu-N2H3, and H-Ala-azaAla-Lys-Glu-Ala-Ala-Glu-Ala-Ala-Glu-Lys-Ala-Ala-Glu-Leu-A la-Leu-N2H3 have been prepared. A new analogue of the Ala-Gly sequence, 3-azaalanylpropionic acid has been prepared and used to prepare the peptide analogue acetyl-Leu-Ser-Gly-azaAla-3-Prop-Phe-Ser-Leu-NH2.

Amino Acid Sequence↗
PubMed1993

A real-time gesture recognizer based on dynamic programming.

Coded gestures are physical movements to which precise meanings have been attached. Their use with an electronic pointing device potentially increases the power of the pointer by allowing several distinct control functions to be incorporated. The formation of a coded gesture is invariably subject to distortions which make its automatic recognition difficult. After particular consideration of three techniques, a dynamic programming algorithm was developed and was used in the design of a real-time gesture recognizer that allows mouse-driven software to be operated purely by means of an electronic pointer. The decision was taken to implement the gesture recognizer using a widely available, obsolescent microcomputer in order to keep down costs. Despite the inevitable technical compromises in this approach, results of preliminary trials using 10 normal subjects show an average gesture recognition rate of 98.3% and a gesture confusion rate of only 0.4%.

Algorithms↗
PubMed1992

Incorporation of azaglutamine residues into peptides synthesised by the ultra-high load solid (gel)-phase technique.

The solid (gel)-phase peptide synthesis of peptides, each containing an azaglutamine residue, has been examined. Procedures using various mono-, di- and tripeptide and carbazate fragments containing or relating to an azaglutamine (1) residue have been evaluated. N-Activation of the amino-terminus of a resin-bound peptide with bis-(2,4-dinitrophenyl)carbonate (2) yielded the terminal isocyanate species, which reacted with protected carbazates to give resin-bound protected peptides containing the aza-residue. By contrast, coupling of activated amino-acid derivates to the free amino-group of a resin-bound peptide with an aza-residue at the N-terminus was a slow and unsatisfactory process. It is concluded that the route yielding the best results involves the reaction of a protected amino-acyl carbazate to a resin-bound isocyanate-activated peptide.

Amino Acid Sequence↗
PubMed1991

Inhibition of trypsin by t-butyloxycarbonyl-alpha-aza-(4-aminophenyl)alanine phenyl ester.

t-Butyloxycarbonyl-alpha-aza-(4-aminophenyl)alanine phenyl ester (III: R = NH2) has been synthesized. The rate of inhibition of trypsin (EC 3.4.21.4) by this compound (due to acylation followed by slower deacylation) shows a marked pH maximum at approximately 6. The shape of the pH-rate curve is discussed in terms of (i) the normal pH-activity curve of trypsin reacting with a charged substrate, i.e. the protonated form of the amino compound, (ii) the deprotonation of the 4-amino group with pKa 4.3, and (iii) the lower rate of reaction of the enzyme with the uncharged, deprotonated form of the ester.

Amino Acids, Diamino↗
PubMed1991

Prostaglandins in the kidney, urinary bladder and gills of the rainbow trout and European eel adapted to fresh water and seawater.

Prostaglandins in kidney, gills, and urinary bladder of freshwater-adapted and seawater-adapted rainbow trout, Oncorhynchus mykiss (= Salmo gairdneri), and European eel, Anguilla anguilla, were determined by solid-phase extraction of tissue homogenates and high-pressure liquid chromatography. Prostaglandins E2, E1, F1 alpha, F2 alpha, and D2 and the more stable metabolite of prostacyclin, 6-keto F1 alpha, occurred in these osmoregulatory tissues. In gill filaments and kidneys of both eel and trout, prostaglandins D2 and 6-keto F1 alpha were major prostaglandins. Concentrations of these prostaglandins were significantly lower in the eel after seawater adaptation, but not in the trout. The urinary bladder of the trout contained the highest levels of prostaglandins; bladders of seawater-adapted trout contained prostaglandin D2 at 6.7 ng/mg wet tissue, the highest level of any prostaglandin determined in the present studies. Prostaglandin D2 was not detected in bladders of freshwater-adapted trout.

Adaptation, Physiological↗
PubMed1990

Immobilization of lipase from Candida cylindraceae and its use in the synthesis of menthol esters by transesterification.

Lipase (EC 3.1.1.3) from Candida cylindraceae has been immobilized by the cellulose-titanium chloride method, and on EP-400 polyethylene, with and without glutaraldehyde crosslinking, to give active preparations when assessed by their ability to catalyse the hydrolysis of tributyrin. In both cases, the use of glutaraldehyde crosslinking was shown to improve the stability of the preparations for repeated use. The lipase immobilized on EP-400 polyethylene was found to be effective in transesterification using tributyrin or triacetin as acyl donors with l-menthol as acceptor. The production of methyl butanoate and of methyl acetate using this immobilized preparation was in each case enhanced in the presence of Amberlite IR 47 Anion exchange resin (OH form).

Candida↗
PubMed1988

Glycoprotein gonadotropins. Structure and synthesis.

The four human glycoprotein hormones FSH, LH, CG and TSH are closely related in structure, each consisting of a common alpha-subunit and a specific beta-subunit. Amino acid sequences have been established by standard methods of protein sequencing and confirmed by base sequencing of the cDNAs encoding for the polypeptide units. Speculation on the structures involved in the binding of subunits and binding to receptors has been based on examination of these sequences for common or similar regions. There are asparagine-linked carbohydrate chains attached to the subunits and in addition O-glycosidically linked carbohydrate chains in beta-CG attached to serine molecules. The carbohydrates are essential for full biological activity. The progress so far and future possibilities for the synthesis of these glycoprotein hormones by the technique of genetic engineering are discussed.

Amino Acid Sequence↗
PubMed1987

Glomerular ultrastructure of the trout, Salmo gairdneri: effects of angiotensin II and adaptation to seawater.

The effect of angiotensin infusion on the glomerular ultrastructure of freshwater- and seawater-adapted rainbow trout. Salmo gairdneri, has been examined by scanning and transmission electron microscopy. Adaptation of trout to seawater resulted in epithelial podocyte flattening, primary process broadening and apparent loss of foot processes in almost all glomeruli, features which were uncommon in freshwater-adapted trout. Similar changes were induced by infusion of freshwater-adapted animals with angiotensin, suggesting that the renin-angiotensin system plays a role in the modification of glomerular epithelial ultrastructure. Adaptation of trout to seawater also reduced glomerular diameter, but infusion of freshwater-adapted animals with angiotensin did not mirror this effect. Infusion of angiotensin into seawater-adapted animals increased the overall thickness of glomerular basement membrane by increasing the lamina rara interna and lamina densa. This did not occur when freshwater-adapted fish were either infused with angiotensin or adapted to seawater. These findings suggest that other humoral systems are involved in the control of glomerular diameter and basement membrane thickness as part of an integrated response to increased environmental salinity.

Acclimatization↗
PubMed1985

Renal and cardiovascular effects of angiotensin II in the rainbow trout, Salmo gairdneri.

The renal and cardiovascular effects of an intravenous infusion of angiotensin II in the freshwater anaesthetised rainbow trout, Salmo gairdneri, have been reappraised, without the infusion of noradrenaline. In these fish the previously reported antidiuretic response to angiotensin II was not maintained although a systemic pressor response persisted and the tubular transport maximum for glucose remained depressed. The data suggest that angiotensin has an intrarenal action which may play a role in renal adaptation to increased environmental salinities.

Angiotensin II↗
PubMed1984

Benzyloxycarbonylphenylalanylcitrulline p-nitroanilide as a substrate for papain and other plant cysteine proteinases.

After preliminary assays, with papain, bromelain and ficin, on a range of citrulline p-nitroanilides, values of Km and kcat. for the papain-catalysed hydrolysis of three derivatives, N alpha- benzyloxycarbonylcitrulline p-nitroanilide, benzyloxycarbonylphenylalanylcitrulline p-nitroanilide and benzyloxycarbonylglycylphenylalanylcitrulline p-nitroanilide, were obtained. It is concluded that benzyloxycarbonylphenylalanylcitrulline p-nitroanilide is a highly selective substrate for the sensitive detection and assay of the plant cysteine proteinases.

Bromelains↗
PubMed1983

Glomerular ultrastructure of the trout, Salmo gairdneri. Glomerular capillary epithelium and the effects of environmental salinity.

The epithelial ultrastructure of the glomerulus of fresh- and sea-water adapted rainbow trout, Salmo gairdneri was examined by scanning and transmission electron microscopy after in vivo-perfusion fixation. Adaptation to seawater for a period of up to 9 weeks was not associated with a change in glomerular size, although after one year in seawater both glomeruli and their capsules were significantly smaller than the glomeruli of freshwater adapted fish. In freshwater adapted trout the epithelial ultrastructure conformed to the general vertebrate pattern, with rounded podocytes, well-defined primary processes and interdigitating pedicels. Adaptation to seawater was associated with a marked increase in the frequency of cytoplasmic microprojections. In many glomeruli there was a flattening of the podocytes, broadening of the primary processes, and areas of closely-packed pedicels were common. These observations are discussed in the light of previous studies on the mammalian kidney and the changes of single nephron function known to be associated with adaptation of trout to increased environmental salinities.

Adaptation, Physiological↗