Purified γ-Glutamyl Transpeptidases from Tomato Exhibit High Affinity for Glutathione and Glutathione<i>S</i>-Conjugates

Martin, Melinda N.; Slovin, Janet P.

doi:10.1104/pp.122.4.1417

Cited by 78 publications

(77 citation statements)

References 37 publications

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“…Such γ-glutamyl peptides may be formed by the reaction of GSH with the ethylene precursor, i.e. 1-aminocyclopropane-1-carboxylic acid, in tomato (MARTIN & SLOVIN 2000) and hypoglycin A in the ackee fruit, respectively (VELÍŠEK et al 2005).…”

Section: Other γ-Glutamyl Peptidesmentioning

confidence: 99%

Biosynthesis of food constituents: Peptides - a review

Velidek¹,

Kubec²,

Cejpek³

2006

Czech J. Food Sci.

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Peptides display a wide variety of biological functions and many of them have remarkable physiological properties. Some are widely distributed in nature and found in many different organisms, whereas others are only of a restricted occurrence. For example, peptides function as neurotransmitters and hormones and thus control many physiological processes. Furthermore, the toxic principles of some plants and mushrooms, insect, snake, and spider venoms are usually peptides.Peptides are biosynthesised by ribosomal and nonribosomal (multi-functional enzyme) processes from a wide range of amino acids. Ribosomal peptide biosynthesis leads to enzymes, peptide hormones, and many other physiologically active peptides. Nonribosomal peptide biosynthesis is responsible for the formation of glutathione, histidine-containing dipeptides of skeletal muscles, peptide toxins, and peptide antibiotics. The mechanisms of these processes are, however, beyond the scope of this review.Many structures biosynthesised by ribosomal processes are additionally modified. Glycopeptides are produced by adding sugar residues via O-glycoside linkages to the hydroxyls of serine and threonine residues or via N-glycoside linkages to the amino group of asparagine. Phosphopeptides and phosphoproteins have the hydroxyl group of serine or threonine esterified with phosphoric acid. Many peptides contain a pyroglutamic (glutiminic) acid residue at the N-terminus, which is a consequence of glutamic acid intramolecular cyclisation between the γ-carboxyl and the α-amino group. The C-terminal carboxylic acids may also frequently be converted to an amide.Nonribosomal processes synthesise many natural peptides occurring in foods. These peptides are formed by a sequence of enzyme-controlled reactions. During these processes, each amino acid (often not encoded by DNA) is added (after activation by conversion into AMP esters) as a result of the specificity of the enzyme involved. This review article gives a brief survey of principal pathways that lead to the biosynthesis of most important peptides occurring in foods. Glutathione, selected plant γ-glutamyl peptides, and animal histidine dipeptides are included in this review. Biosynthesis of Food

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Section: Other γ-Glutamyl Peptidesmentioning

confidence: 99%

Biosynthesis of food constituents: Peptides - a review

Velidek¹,

Kubec²,

Cejpek³

2006

Czech J. Food Sci.

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“…All of the enzymes in this cycle are reported in plants except the Cys-Gly dipeptidase. Soluble and bound GGT activity has been detected in tomato (Solanum lycopersicum), onion (Allium cepa), radish (Raphanus sativus), and Arabidopsis (Martin and Slovin, 2000;Storozhenko et al, 2002;Nakano et al, 2004;Shaw et al, 2005;Grzam et al, 2007;Martin et al, 2007;Ohkama-Ohtsu et al, 2007a, 2007b. Recently, we analyzed the functions of Arabidopsis GGT proteins using knockout mutants (Ohkama-Ohtsu et al, 2007a, 2007b.…”

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confidence: 99%

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

et al. 2008

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The degradation pathway of glutathione (GSH) in plants is not well understood. In mammals, GSH is predominantly metabolized through the g-glutamyl cycle, where GSH is degraded by the sequential reaction of g-glutamyl transpeptidase (GGT), g-glutamyl cyclotransferase, and 5-oxoprolinase to yield glutamate (Glu) and dipeptides that are subject to peptidase action. In this study, we examined if GSH is degraded through the same pathway in Arabidopsis (Arabidopsis thaliana) as occurs in mammals. In Arabidopsis, the oxoprolinase knockout mutants (oxp1-1 and oxp1-2) accumulate more 5-oxoproline (5OP) and less Glu than wild-type plants, suggesting substantial metabolite flux though 5OP and that 5OP is a major contributor to Glu steady-state levels. In the ggt1-1/ggt4-1/oxp1-1 triple mutant with no GGT activity in any organs except young siliques, the 5OP concentration in leaves was not different from that in oxp1-1, suggesting that GGTs are not major contributors to 5OP production in Arabidopsis. 5OP formation strongly tracked the level of GSH in Arabidopsis plants, suggesting that GSH is the precursor of 5OP in a GGT-independent reaction. Kinetics analysis suggests that g-glutamyl cyclotransferase is the major source of GSH degradation and 5OP formation in Arabidopsis. This discovery led us to propose a new pathway for GSH turnover in plants where GSH is converted to 5OP and then to Glu by the combined action of g-glutamyl cyclotransferase and 5-oxoprolinase in the cytoplasm.

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“…İleriye dönük epidemiyolojik çalışmalar, Toplumda GGT değerlerindeki değişiklik ile mortalite ve morbidite arasındaki ilişkiyi ve tip 2 diabetes mellitus, koroner arter hastalığı riski ile GGT bağlan-tısını göstermiştir. (5,6) Sonuç olarak, toplumda normal yüksek, hafif yüksek GGT seviyelerinin taranması, mortalite açısından yüksek riskli hastaların tanımlanmasını sağlayabilir.…”

Section: Introductionunclassified

The Predictive Value Of Gamma-Glutamyl Transferase In Acute Myocardial Infarction And Ischemic Stroke

Emen¹,

Can²,

Üstündağ³

et al. 2011

Tepecik Dergisi

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ÖZETAmaç: Akut miyokard infarktüsü (AMİ) ve iskemik inmeli olgular ile gama glutamil transferaz (GGT) düzeyleri arasındaki ilişkiyi incelemek. Gereç ve Yöntem:Sınıflandırma için Dünya Sağlık Örgütünün belirlediği kriterler kullanıldı. 110 (26 kadın, 84 erkek) akut miyokard infarktüsü hastası ve 43 (17 kadın, 26 erkek) iskemik inmeli hasta çalışmaya alındı. Olgular akut miyokard infarktüsü, iskemik inme ve hipertansif kontrol grubu olarak üçe ayrıldı. Bulgular: Akut miyokard infarktüsü ve iskemik inme geçiren olgular ayrı ayrı ele alındığında kontrol grubuna göre daha fazla GGT yüksekliğine rastlandı, sırasıyla (p=<0,01) ve (p<0,05). Tüm hasta grupları ele alındığında kontrol grubuna göre daha fazla GGT yüksekliğine rastlandı. (p=<0,01).Sonuç: GGT enziminin; ateroskleroz ile ilişkili olduğu, kardiyovasküler ve serebrovasküler hastalık riskini öngören, basit ve ucuz bir laboratuvar testi olarak kullanılabileceği düşünülebilir.Anahtar Sözcükler: Gama glutamil transferaz,iskemik inme,miyokard infarktüsü.

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Purified γ-Glutamyl Transpeptidases from Tomato Exhibit High Affinity for Glutathione and GlutathioneS-Conjugates

Cited by 78 publications

References 37 publications

Biosynthesis of food constituents: Peptides - a review

Biosynthesis of food constituents: Peptides - a review

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

The Predictive Value Of Gamma-Glutamyl Transferase In Acute Myocardial Infarction And Ischemic Stroke

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