Role Of Serine Research Articles

Serine-202 is the putative precursor of the active site dehydroalanine of phenylalanine ammonia lyase Site-directed mutagenesis studies on the enzyme from parsley ( Petroselinum crispum L.)

To investigate the possible role of serine as a precursor of dehydroalanine at the active site of phenylalanine ammonia lyase, two serines, conserved in all known PAL and histidase sequences, were changed to alanine by site-directed mutagenesis. The resulting mutant genes were subcloned into the expression vector pT7.7 and the gene products were assayed for PAL activity. Mutant PALMutS209A showed the same catalytic property as wild-type PAL, whereas mutant PALMutS202A was devoid of catalytic activity, indicating that serine-202 is the most likely precursor of the active site dehydroalanine.

Two-dimensional, rotational-echo double-resonance NMR of cell culture metabolism.

Two-dimensional, rotational-echo double-resonance 13C NMR, a new solid-state NMR technique, has been used to show that the relative fluxes of the labeled chemical bond of L-[2-13C,15N]serine along four metabolic pathways (direct purine synthesis, direct glycine incorporation into protein, direct non-glycyl incorporation into protein, and nitrogen scrambling with loss of carbon) are 1:2:6:36, respectively, for Klebsiella pneumoniae under conditions of nitrogenase derepression. These determinations were performed on a single sample of lyophilized, double-labeled, intact cells. Analysis of the homogeneity of the distribution of label suggests that the primary role of serine in shortening derepression is in providing specific carbon and nitrogen for RNA synthesis.

Serine regulates phosphatidylethanolamine biosynthesis in the hamster heart.

The role of serine as a precursor and metabolic regulator for phosphatidylethanolamine biosynthesis in the hamster heart was investigated. Hearts were perfused with 50 microM [1-3H]ethanolamine in the presence or absence of serine for up to 60 min. Ethanolamine uptake was attenuated by 0.05-10 mM serine in a noncompetitive manner, and the incorporation of labeled ethanolamine into phosphatidylethanolamine was also inhibited by serine. Analysis of the ethanolamine-containing metabolites in the CDP-ethanolamine pathway revealed that the conversion of ethanolamine to phosphoethanolamine was reduced. The reduction was a result of an inhibition of ethanolamine kinase activity by an elevated pool of intracellular serine. Perfusion of the heart with 1 mM serine caused a 5-fold increase in intracellular serine pool. In order to examine the action of serine on other phosphatidylethanolamine metabolic pathways, hearts were perfused with [1-3H]glycerol in the presence and absence of serine. Serine did not cause any enhancement of phosphatidylethanolamine hydrolysis. The base-exchange reaction for phosphatidylserine formation or the decarboxylation of phosphatidylserine was not affected by serine perfusion. We conclude that circulating serine plays an important role in the modulation of phosphatidylethanolamine biosynthesis via the CDP-ethanolamine pathway in the hamster heart but does not affect the contribution of the decarboxylase pathway for phosphatidylethanolamine formation.

Mechanisms of neutrophil damage to human alveolar extracellular matrix: The role of serine and metalloproteases

Many syndromes of lung injury are associated with accumulation of neutrophils within the pulmonary parenchyma. These neutrophils have the capacity to produce lung injury by products including proteases and reactive oxygen species (ROS). We examined the ability of activated neutrophils to solubilize human alveolar extracellular matrix (ECM), and by use of scavengers and inhibitors, evaluated the role of ROS and proteases in this process. Supernatants of phorbol myristate acetate-activated neutrophils routinely solubilized 10.2% ± 0.8% (n = 30) of collagen in human alveolar ECM, as measured by hydroxyproline release. Scavengers of ROS had no significant effect on ECM solubilization. Inhibitors of metalloproteases partially inhibited ECM solubilization (38.5% ± 4.6% inhibition by ethylenediaminetetraacetic acid [n = 6], and 37.0% ± 14.7% by 1,10-phenanthroline [n = 6]; p < 0.05). Inhibitors of the neutrophil serine proteases, elastase and cathepsin G, markedly inhibited ECM solubilization (100.9% ± 3.7% by α 1-protease inhibitor [α 1-PI] [n = 6] and 81.9% ± 0.1% by soybean trypsin inhibitor [n = 6]; p < 0.01). Since α 1-PI completely inhibited solubilization, metalloprotease activity appeared to be related to serine protease activity. This finding was confirmed by the observation that addition of a metalloenzyme activator, p-aminophenylmercuric acetate, in the presence of α 1-PI, restored solubilization to the same level as that inhibited by metal chelators. We conclude that human neutrophil metalloproteases and serine proteases directly solubilize human alveolar ECM. Furthermore, neutrophil serine proteases activate latent metalloproteases. However, ROS were not demonstrated to play a major role in ECM solubilization in our system.

Removal of an inter-domain hydrogen bond through site-directed mutagenesis: role of serine 176 in the mechanism of papain

A mutant of papain, where an inter-domain hydrogen bond between the side chain hydroxyl group of a serine residue at position 176 and the side chain carbonyl oxygen of a glutamine residue at position 19 has been removed by site-directed mutagenesis, has been produced and characterized kinetically. The mutation of Ser176 to an alanine has only a small effect on the kinetic parameters, the kcat/Km for hydrolysis of CBZ-Phe-Arg-MCA by the Ser176Ala enzyme being of 8.1 x 10(4) /M/s compared with 1.2 x 10(5) /M/s for papain. Serine 176 is therefore not essential for the catalytic functioning of papain, even though this residue is conserved in all cysteine proteases sequenced. The pH-activity profiles were shown to be narrower in the mutant enzyme by up to 1 pH unit at high ionic strength. This result is interpreted to indicate that replacing Ser176 by an alanine destabilizes the thiolate-imidazolium form of the catalytic site Cys25-His159 residues of papain. Possible explanations for that effect are given and the role of a serine residue at position 176 in papain is discussed.

Isolation of protein-glycogen complexes from rat skeletal muscle in acute uremia: role of serine.

AbstractAttempts were made to isolate an intact protein–glycogen complex from rat skeletal muscle in acute and chronic uremia and after different treatment regimes. In control animals the amount of glycogen in the 30-pellet fraction was 16.5 mg and in rats with chronic uremia 27.6 mg. The yields of glycogen phosphorylase and synthetase do not correlate with the quantity of glycogen during isolation. In the presence of ATP, calcium, and magnesium, flash activation of phosphorylase was four to six times slower in rat than in rabbit muscle. In acute uremia, after feeding a mixed low-protein diet and Walser ketoacid mixture, a protein–glycogen complex could not be isolated. Additional administration of propranolol resulted in yields of only 10 and 7 μg glycogen after binephrectomy and ureter ligation, respectively. In contrast, glycogen concentration increased dramatically after sham operation (4.55 mg glycogen/mg protein). Additional administration of high doses of serine resulted in an increase of glycogen ...

Carbon-13 NMR spectroscopy of [20%-1,2-13C2-Gly6]-bradykinin. Role of serine in reducing structural heterogeneity

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-13 NMR spectroscopy of [20%-1,2-13C2-Gly6]-bradykinin. Role of serine in reducing structural heterogeneityRobert E. London, John M. Stewart, Robert Williams, John R. Cann, and N. A. MatwiyoffCite this: J. Am. Chem. Soc. 1979, 101, 9, 2455–2462Publication Date (Print):April 1, 1979Publication History Published online1 May 2002Published inissue 1 April 1979https://doi.org/10.1021/ja00503a035RIGHTS & PERMISSIONSArticle Views45Altmetric-Citations33LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (953 KB) Get e-Alerts Get e-Alerts

The role of serine in the lipid metabolism of the rat tapeworm Hymenolepis diminuta

Webb R. A. and Mettrick D. F. 1973. The role of serine in the lipid metabolism of the rat tapeworm Hymenolepis diminuta. International Journal for Parasitology 3: 47–58. The inter-relationship between the amino acid serine and lipid metabolism in the rat tapeworm Hymenolepis diminuta has been studied under in vitro conditions. The label from U- 14C-serine, U- 14C-glucose and 1- 14C-oleic acid was rapidly incorporated into worm tissue phospho- and glycolipids, the latter illustrating the synthesis of cerebrosides by H. diminuta. Activity from U- 14C-serine was recovered in phosphatidylserine, phosphatidylethanolamine, cerebrosides and several unidentified lipid-like compounds. The majority of the label recovered in phosphatidylethanolamine was associated with the ethanolamine moiety; in the cerebrosides with the sphingosine moiety. The sugar moiety of the cerebrosides was galactose. Pulse label studies showed a serine flux phenomenon, and a rapid rate of turnover of some of the unidentified compounds. Exogenous ethanolamine had no detectable effect upon absorption and conversion of serine to tissue phosphatidylethanolamine. Incubation of H. diminuta homogenates with phosphatidyl U- 14C-serine resulted in the recovery of considerable activity in phosphatidylethanolamine. The results show that the major pathway of phosphatidylethanolamine synthesis is by decarboxylation of phosphatidylserine.

The Role of Serine in the Linkage of Heparin to Protein

SUMMARY A number of commercial heparin preparations have been examined for the presence of amino acids. Heparin which had been prepared by use of mild methods essentially based on treat- ment with proteolytic enzymes, contained residual amino acids with serine as the main component. In some preparations serine was the only amino acid found in significant amounts. Samples prepared under more drastic conditions, including alkali extrac- tion and bleaching at elevated temperatures, contained only traces of amino acids. It is suggested that heparin occurs in the native state as a complex with protein and that the carbohydrate- protein linkage is similar to that of the chondroitin 4-sulfate- protein complex. dcknowledgments-We are indebted to Professor E. Jorpes, Karolinska Institutet, Stockholm, Mr. G. Linden, the Vitrum AB, Dr. H. H. R. Weber, and Dr. C. DeFiebre, Wilson Labora- tories, and to Dr. L. L. Coleman, the Upjohn Company, for providing the heparin samples. We are also grateful to the Vitrum AB and the Wilson Laboratories for the anticoagulant activity assays. We are grateful to Dr. A. Dorfman for stimulat- ing discussions and continued support throughout this work. We wish to thank Dr. M. B. Mathews for the molecular weight determinations and Miss M. L. Spach for skillful technical assist- ance.

CARBON METABOLISM OF GLYCINE AND SERINE IN RELATION TO THE SYNTHESIS OF ORGANIC ACIDS AND A GUANINE DERIVATIVE.

The metabolism of glycine or serine in aninmals alnd niicroorganisms has been well documented. The catabolism of glycine by way of glyoxylate is by far the 1mnost imiiportalnt pathway in mammalian tissues (9,10) and in microorganisms (2). Glyoxylate could be formiied from glycine either by the action of glycine oxidase (14) or by transamination (8,11). The metabolic conversion of serine to glycine and a 1-carhon uinit is reversible and has been denmonstrated to occur in animals (5) and plants (6,7,20). lHowever, in wheat leaves, glycine is converted preferentially to serine (16,17). The conversion of serine to glycine in vivo in wheat leaves proceeds very slowly (16,17). Wang and Waygood (18) investigated the conversion of glycine to sugars in wheat leaves and proposed a glyoxylate-serine pathway in wvhich serine occupies a key position as an essenitial internmediate. Rabson et al. (13) also have discussed the glycolate pathway for the production of precursors of hexoses. Recently, the role of serine in glycinie metabolism has been clearly demonstrated by Wang and Burris (16,17), and glyceric acid has been implicated as an intermediate between serine and hexoses (13,16,17,18). In additioni to the transformation of glycine or serine to hexoses, a considerable portion of either amino acid is utilized for the synthesis of a number of acidic compounds (15-18). The type of compotunds derived fromii these amino acids, besides glyceric and glycolic acids, had not been investigated fully, and the present communication deals with some of the fin(dinigs fromii a study of these compotnll(s.

A Mutational Alteration of the Tryptophan Synthetase of Escherichia coli

SUMMARY: A tryptophan auxotroph of Escherichia coli produced an altered tryptophan synthetase which could not convert indole to tryptophan but converted indole-3-glycerol phosphate to indole. As distinct from the normal tryptophan synthetase, which also catalysed this reaction, both pyridoxal phosphate and serine stimulated the activity of the mutant enzyme system. Fractionation and chromatography of the mutant tryptophan synthetase separated it into its two protein components, A and B. Examinations of the separated components showed that the A protein was normal, while the B protein was altered. Studies of the effect of serine on the pH-activity response of mutant preparations in the indole-3-glycerol phosphate → indole reaction demonstrated that different pH-activity responses were obtained, respectively, in the presence and absence of serine. The curves obtained were characteristic of the serine-requiring and serine-non-requiring reactions, respectively, of normal tryptophan synthetase. The saturation curves of the mutant component B by normal component A, with and without serine added, suggest that one role of serine and pyridoxal phosphate in the stimulation of the indole-3-glycerol phosphate → indole reaction is to bind together the A and B proteins in a catalytically effective complex.