Amino acids and related compounds in the lens

Calam, D.H.; Waley, S. G.

doi:10.1042/bj0930526

Cited by 18 publications

(3 citation statements)

References 28 publications

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“…The components in the extract were separated by low-voltage paper electrophoresis (Whatman no. 52 paper) at pH 1.6 followed by paper chromatography at right angles in solvent 1 (see below), essentially as described by Calam (1962) and Calam & Waley (1964). The papers were then radioautographed and the radioactive spots tentatively identified by reference to markers, and a published 'map' for lens extracts (Calam, 1962), and by the use of ninhydrin (Atfield & Morris, 1961) and isatin (Smith, 1969) stains.…”

Section: Methodsmentioning

confidence: 99%

The metabolism of amino acids in the bovine lens. Their oxidation as a source of energy

Trayhurn

Heyningen

1973

Biochemical Journal

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1. The metabolism by the bovine lens of nine (14)C-labelled l-amino acids was studied. These were: alanine, aspartate, glutamate, leucine, lysine, proline, serine, tyrosine and tryptophan. 2. All were taken up by the tissue and incorporated into protein. 3. Aspartate and glutamate, although poorly taken up, were readily metabolized to CO(2). Radioactivity from glutamate was also found in glutathione, glutamine, proline and ophthalmic acid. Aspartate was converted into glutamate, glutathione, proline, alanine and lactate. 4. Alanine was largely converted into lactate, which was released into the medium, but incorporation of radioactivity into CO(2), glutamate, glutathione, aspartate and lipids also occurred. 5. Radioactivity from leucine was detected in CO(2), lipids, glutamate, glutathione, proline and glutamine. 6. Lysine was only slightly broken down by the bovine lens; radioactivity was observed in CO(2), glutamate, glutathione, proline and two unidentified compounds. 7. Proline was metabolized to glutamate from which CO(2), glutathione and glutamine were formed. Hydroxyproline in the capsule collagen was labelled. 8. Radioactivity from serine was found in CO(2), lipids, glutathione, glycine, cystine, ATP, lactate and three unidentified compounds, one of which was probably taurine. 9. Neither tyrosine nor tryptophan were metabolized by the bovine lens. 10. The ability of the lens to metabolize amino acids was also shown by measurement of NH(3) production: more NH(3) was formed when glucose was absent from the incubation medium. 11. These experiments suggest that oxidation of amino acids is a source of energy for the lens.

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Section: Methodsmentioning

confidence: 99%

The metabolism of amino acids in the bovine lens. Their oxidation as a source of energy

Trayhurn

Heyningen

1973

Biochemical Journal

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“…Some authors have reported the absence of HCD from liver (95,96), whereas Purchas and Busboom (307) have reported very high bovine liver carnosine concentrations in the low end of the concentration range found in skeletal muscles (ϳ4 mmol/kg). Others found trace amounts of carnosine in tissues such as the bovine lens (77). Part of the contradiction in the literature may have arisen from the fact that 1) carnosine concentrations in various tissues are at the limit of detection, 2) there are significant interspecies differences, and/or 3) there is a large difference in the accuracy of HCD quantification between the different analytic methodologies.…”

Section: B Distribution Of Hcd In Tissuesmentioning

confidence: 98%

Physiology and Pathophysiology of Carnosine

Boldyrev

Aldini

Derave

2013

Physiological Reviews

870

1,023

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Carnosine (β-alanyl-l-histidine) was discovered in 1900 as an abundant non-protein nitrogen-containing compound of meat. The dipeptide is not only found in skeletal muscle, but also in other excitable tissues. Most animals, except humans, also possess a methylated variant of carnosine, either anserine or ophidine/balenine, collectively called the histidine-containing dipeptides. This review aims to decipher the physiological roles of carnosine, based on its biochemical properties. The latter include pH-buffering, metal-ion chelation, and antioxidant capacity as well as the capacity to protect against formation of advanced glycation and lipoxidation end-products. For these reasons, the therapeutic potential of carnosine supplementation has been tested in numerous diseases in which ischemic or oxidative stress are involved. For several pathologies, such as diabetes and its complications, ocular disease, aging, and neurological disorders, promising preclinical and clinical results have been obtained. Also the pathophysiological relevance of serum carnosinase, the enzyme actively degrading carnosine into l-histidine and β-alanine, is discussed. The carnosine system has evolved as a pluripotent solution to a number of homeostatic challenges. l-Histidine, and more specifically its imidazole moiety, appears to be the prime bioactive component, whereas β-alanine is mainly regulating the synthesis of the dipeptide. This paper summarizes a century of scientific exploration on the (patho)physiological role of carnosine and related compounds. However, far more experiments in the fields of physiology and related disciplines (biology, pharmacology, genetics, molecular biology, etc.) are required to gain a full understanding of the function and applications of this intriguing molecule.

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“…4 is the theoretical curve predicted by eq. [8] for the values listed in Table 1 for K, and K5. Microconstants were calculated from the macroconstants by calculating with eq.…”

Section: Penicillamine-glutathione Mixed Disulfidementioning

confidence: 99%

Nuclear magnetic resonance studies of the acid–base chemistry of amino acids and peptides. IV. Mixed disulfides of cysteine, penicillamine, and glutathione

Theriault¹,

Cheesman²,

Arnold³

et al. 1984

Can. J. Chem.

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. Can. J. Chem. 62, 13 12 (1984). The acid-base chemistry of the ammonium groups of penicillamine-glutathione mixed disulfide and cysteine-glutathione mixed disulfide has been characterized by I3C nmr and that for the ammonium groups of penicillamine-cysteine mixed disulfide by 'H nmr. ' The mixed disulfides were formed by thiol/disulfide exchange. Chemical shift titration data were obtained simultaneously for the mixed disulfides, the thiols, and the symmetrical disulfides in the mixture. Since the fractional titration of individual ammonium groups can be obtained directly from chemical shift data, it was not necessary to isolate the mixed disulfides. The chemical shift data indicate that the two ammonium groups of each of the mixed disulfides are titrated over the same pH range, with the acidity of the ammonium group of the penicillamine and cysteine parts of the penicillamineglutathione and cysteine-glutathione mixed disulfides 4.4 and 3.9 times as acidic as those of the glutathione part. In the penicillamine-cysteine mixed disulfide, the penicillamine ammonium group is 1.7 times as acidic as that of the cysteine part. Macroscopic and microscopic acid dissociation constants are reported for each of the mixed disulfides. The advantages of nmr as a method for characterizing the acid-base chemistry of mixed disulfides are discussed.YVON THERIAULT, BRUCE V. CHEESMAN, ALAN P. ARNOLD et DALLAS L. RABENSTEIN. Can. J. Chem. 62, 13 12 (1984). On a caractCrisC la chimie acide-base des groupes ammonium des disulfures mixtes pCnicillamine-glutathion et cystCine-glutathion en faisant appel 21 la rmn du I3C et celle des groupes ammonium du disulfure mixte penicillamine-cysttine par la rmn du 'H. Les disulfures mixtes ont CtC obtenus via un tchange thiol/disulfure. On a obtenu simultankment les donnCes de titrage du diplacement chimique pour les disulfures mixtes, les thiols et les disulfures symktriques du melange. I1 n'est pas nicessaire d'isoler les disulfures mixtes puisqu'on peut obtenir directement le titrage fractionnel des groupes ammonium individuels B partir des donnCes de dtplacement chimique. Ces donnCes indiquent que les deux groupes ammonium de chaque disulfure sont titrCs dans le m&me domaine de pH. Les aciditis des groupes ammonium des portions pCnicillamine et cystkine des disulfures mixtes pinicillamine-glutathion et cystkine-glutathion sont respectivement 4,4 et 3,9 fois plus tlevies que celle de la partie glutathion. Dans le disulfure mixte p6nicillamine-cystkine 1'aciditC du groupe ammonium de la ptnicillamine est de 1,7 fois plus ClevCe que celle de la cystiine. On rapporte les constantes macroscopique et microscopique de dissociation acide pour chaque disulfure mixte. On discute des avantages de la rmn en tant que mtthode de caracttrisation de la chimie acide-base des disulfures mixtes.[Traduit par le journal] Introduction Thiols are oxidized by disulfides in two steps:

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Amino acids and related compounds in the lens

Cited by 18 publications

References 28 publications

The metabolism of amino acids in the bovine lens. Their oxidation as a source of energy

The metabolism of amino acids in the bovine lens. Their oxidation as a source of energy

Physiology and Pathophysiology of Carnosine

Nuclear magnetic resonance studies of the acid–base chemistry of amino acids and peptides. IV. Mixed disulfides of cysteine, penicillamine, and glutathione

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