RESUMO
BACKGROUND: Pepsin (porcine stomach mucosa, E.C. 3.4.23.1), an acid protease catalyzes the hydrolysis (debranching) of guar galactomannan (GG), a co-polymer of mannose and galactose residues thereby showing its non-specific catalysis towards glycosidic substrates. RESULTS AND CONCLUSIONS: Use of non-specific inhibitors, chemical modification agents and peptide mapping of native and GG--bound pepsin upon proteolytic digestion with Staphylococcus aureus V8 protease revealed the involvement of Asp(138) residue in the catalysis, which was confirmed by computational modelling studies. GENERAL SIGNIFICANCE: Here we show a novel mode of catalysis (other than proteolysis) by porcine pepsin with a different active site residue.
Assuntos
Cyamopsis/química , Mananas/metabolismo , Pepsina A/metabolismo , Sequência de Aminoácidos , Animais , Catálise , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Cristalografia por Raios X , Galactose/análogos & derivados , Simulação de Acoplamento Molecular , Dados de Sequência Molecular , Eletroforese em Gel de Poliacrilamida Nativa , Pepsina A/química , Mapeamento de Peptídeos , Homologia de Sequência de Aminoácidos , SuínosRESUMO
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Diabetes is a chronic health problem and major cause of death in most of the countries. Diet management plays an important role in controlling diabetes and its complications along with insulin and drugs. We have examined the effect of banana (Musa sp. var. elakki bale) flower and pseudostem on hyperglycemia and advanced glycation end-products (AGEs) in streptozotocin-induced diabetic rats. Our results indicated that banana flower and pseudostem have low glycemic index and have a high content of dietary fiber and antioxidants. Diabetic symptoms like hyperglycemia, polyuria, polyphagia, polydipsia, urine sugar, and body weight were ameliorated in banana flower- and pseudostem-treated rats. Increased glomerular filtration rate in the diabetic group (5.1 ± 0.22 ml/min) was decreased in banana flower-fed (2.5 ± 0.37 ml/min) and pseudostem-fed (3.0 ± 0.45 ml/min) groups and were significant at P < 0.001 and P < 0.01, respectively. Fructosamine and AGEs formed during diabetes were inhibited in treated groups when compared with the diabetic group. The diabetic group showed 11.5 ± 0.64 ìg of AGEs/mg protein in kidney, whereas, in banana flower- and pseudostem-fed groups, it was reduced to 9.21 ± 0.32 and 9.29 ± 0.24 ìg/mg protein, respectively, and were significant at P < 0.01. These findings suggest that banana flower and pseudostem have anti-diabetic and anti-AGEs properties and are beneficial as food supplements for diabetics (AU)
Assuntos
Animais , Ratos , Musa , Flores , Extratos Vegetais/farmacocinética , Hiperglicemia/tratamento farmacológico , Produtos Finais de Glicação Avançada , Modelos Animais de Doenças , Substâncias Protetoras/farmacocinética , Diabetes Mellitus/tratamento farmacológico , Estreptozocina/farmacocinéticaRESUMO
Diabetes is a chronic health problem and major cause of death in most of the countries. Diet management plays an important role in controlling diabetes and its complications along with insulin and drugs. We have examined the effect of banana (Musa sp. var. elakki bale) flower and pseudostem on hyperglycemia and advanced glycation end-products (AGEs) in streptozotocin-induced diabetic rats. Our results indicated that banana flower and pseudostem have low glycemic index and have a high content of dietary fiber and antioxidants. Diabetic symptoms like hyperglycemia, polyuria, polyphagia, polydipsia, urine sugar, and body weight were ameliorated in banana flower- and pseudostem-treated rats. Increased glomerular filtration rate in the diabetic group (5.1 ± 0.22 ml/min) was decreased in banana flower-fed (2.5 ± 0.37 ml/min) and pseudostem-fed (3.0 ± 0.45 ml/min) groups and were significant at P < 0.001 and P < 0.01, respectively. Fructosamine and AGEs formed during diabetes were inhibited in treated groups when compared with the diabetic group. The diabetic group showed 11.5 ± 0.64 µg of AGEs/mg protein in kidney, whereas, in banana flower- and pseudostem-fed groups, it was reduced to 9.21 ± 0.32 and 9.29 ± 0.24 µg/mg protein, respectively, and were significant at P < 0.01. These findings suggest that banana flower and pseudostem have anti-diabetic and anti-AGEs properties and are beneficial as food supplements for diabetics.
Assuntos
Diabetes Mellitus Experimental/dietoterapia , Flores , Hiperglicemia/dietoterapia , Musa , Caules de Planta , Animais , Glicemia , Peso Corporal , Carboidratos/urina , Diabetes Mellitus Experimental/metabolismo , Ingestão de Líquidos , Ingestão de Energia , Frutosamina/sangue , Frutosamina/metabolismo , Produtos Finais de Glicação Avançada/sangue , Produtos Finais de Glicação Avançada/metabolismo , Índice Glicêmico , Rim/metabolismo , Fígado/metabolismo , Ratos , Ratos Wistar , EstreptozocinaRESUMO
Pullulanase (EC 3.2.1.41) from Bacillus acidopullulyticus could preferentially remove galactose residues from guar galactomannan (GG), a heteropolymer consisting of polymannan backbone with alternating galactose as single-residue side-chain stubs. The enzyme showed maximum activity at pH 4.5 and 45 degrees C and exhibited Michaelis-Menten kinetics with a K(m) and V(max) of 6.0 mg mL(-1) and 1820 nmol min(-1) mg(-1), respectively. The native and modified GG had a viscosity of 4800 and 3800 cps, respectively. The molecular mass of the enzyme-treated GG varied between 152 +/- 0.5 kDa, and its GLC analysis revealed a significant change in galactose-mannose content of 1:3.8, respectively, similar to that of locust bean gum (LBG). FTIR and solid-state CP-MASS (13)C NMR analyses indicated subtle changes in the conformation of modified GG because of the removal of galactose residues. Gel-strength measurements with kappa-carrageenan showed an improvement in the gelling behavior, similar to that shown by LBG. Debranching of GG by pullulanase is an alternative and inexpensive route to produce modified GG with enhanced functional properties, as a cost-effective replacement for LBG.
