Találati lista | Tudóstér

001-es BibID:	BIBFORM003891
Első szerző:	Gyémánt Gyöngyi (vegyész)
Cím:	Evidence for pentagalloyl glucose binding to human salivary α-amylase through aromatic amino acid residues / Gyöngyi Gyémánt, Ágnes Zajácz, Bálint Bécsi, Chandran Ragunath, Narayanan Ramasubbu, Ferenc Erdődi, Gyula Batta, Lili Kandra
Dátum:	2009
ISSN:	1570-9639
Megjegyzések:	We demonstrate here that pentagalloyl glucose (PGG), a main component of gallotannins, was an effective inhibitor of HSA and it exerted similar inhibitory potency to Aleppo tannin used in this study. The inhibition of HSA by PGG was found to be non-competitive and inhibitory constants of KEI = 2.6 ?M and KESI = 3.9 ?M were determined from Lineweaver-Burk secondary plots. PGG as a model compound for gallotannins was selected to study the inhibitory mechanism and to characterize the interaction of HSA with this type of molecules. Surface plasmon resonance (SPR) binding experiments confirmed the direct interaction of HSA and PGG, and it also established similar binding of Aleppo tannin to HSA. Saturation transfer difference (STD) experiment by NMR clearly demonstrated the aromatic rings of PGG may be involved in the interaction suggesting a possible stacking with the aromatic side chains of HSA. The role of aromatic amino acids of HSA in PGG binding was reinforced by kinetic studies with the W58L and Y151M mutants of HSA: the replacement of the active site aromatic amino acids with aliphatic ones decreased the PGG inhibition dramatically, which justified the importance of these residues in the interaction.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Molekulatudomány pentagalloyl glucose human salivary alpha-amylase inhibition surface plasmon resonance saturation transfer difference NMR
Megjelenés:	Biochimica et Biophysica Acta (BBA). Proteins and Proteomics. - 1794 : 2 (2009), p. 291-296. -
További szerzők:	Zajácz Ágnes Bécsi Bálint (1981-) (vegyészmérnök) Ragunath, Chandran Ramasubbu, Narayanan Erdődi Ferenc (1953-) (biokémikus) Batta Gyula (1953-) (molekula-szerkezet kutató) Kandra Lili (1943-) (biokémikus)
Pályázati támogatás:	TÁMOP-4.2.2-08/1-2008-0019 TÁMOP
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI Szerző által megadott URL
Borító:
Saját polcon:

001-es BibID:	BIBFORM084730
Első szerző:	Kandra Lili (biokémikus)
Cím:	Inhibitory effects of tannin on human salivary α-amylase / Kandra Lili, Gyémánt Gyöngyi, Zajácz Ágnes, Batta Gyula
Dátum:	2004
ISSN:	0006-291X
Megjegyzések:	Here, we first report on the effectiveness and specificity of tannin inhibition of 2-chloro-4-nitrophenyl-4-O-β-d-galactopyranosylmaltoside hydrolysis that is catalyzed by human salivary α-amylase (HSA). Tannin was gallotannin in which quinic acid was esterified with 2-7 units of gallic acid. A number of studies establish that polyphenols-like tannins-may prevent oral diseases, e.g., dental caries. Kinetic analyses confirmed that the inhibition of hydrolysis is a mixed non-competitive type and only one molecule of tannin binds to the active site or the secondary site of the enzyme. Since Dixon plots were linear, product formation could be excluded from the enzyme-substrate-inhibitor complex (ESI). Kinetic constants calculated from secondary plots and non-linear regression are almost identical, thereby confirming the suggested model. Kinetic constants (KEI=9.03 ?g mL?1, KESI=47.84 ?g mL?1) show that tannin is as an effective inhibitor of HSA as acarbose and indicate a higher stability for the enzyme-inhibitor complex than ESI.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk Human salivary a-amylase Tannin Gallotannin Quinic acid Inhibition Mixed non-competitive
Megjelenés:	Biochemical And Biophysical Research Communications. - 319 : 4 (2004), p. 1265-1271. -
További szerzők:	Gyémánt Gyöngyi (1960-) (vegyész) Zajácz Ágnes Batta Gyula (1953-) (molekula-szerkezet kutató)
Pályázati támogatás:	T042567 OTKA T043499 OTKA M041829 OTKA
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
Borító:
Saját polcon:

001-es BibID:	BIBFORM079354
Első szerző:	Kandra Lili (biokémikus)
Cím:	Kinetic investigation of a new inhibitor for human salivary α-amylase / Kandra Lili, Zajácz Ágnes, Remenyik Judit, Gyémánt Gyöngyi
Dátum:	2005
ISSN:	0006-291X
Megjegyzések:	This study is the first report on the effectiveness and specificity of ?-acarviosinyl-(1 ? 4)-?-d-glucopyranosyl-(1 ? 6)-d-glucopyranosylidene-spiro-thiohydantoin (PTS-G-TH) inhibitor on the 2-chloro-4-nitrophenyl-4-O-?-d-galactopyranosyl-maltoside (GalG2CNP) and amylose hydrolysis catalysed by human salivary ?-amylase (HSA). Synthesis of PTS-G-TH was carried out by transglycosylation using acarbose as donor and glucopyranosylidene-spiro-thiohydantoin (G-TH) as acceptor. This new compound was found to be a much more efficient HSA inhibitor than G-TH. The inhibition is a mixed-noncompetitive type on both substrates and only one molecule of inhibitor binds to the enzyme. Kinetic constants calculated from secondary plots are in micromolar range. Values of KEI and KESI are very similar in the presence of GalG2CNP substrate; 0.19 and 0.24 ?M, respectively. Significant difference can be found for KEI and KESI using amylose as substrate; 8.45 and 0.5 ?M, respectively. These values indicate that inhibition is rather uncompetitive than competitive related to amylose hydrolysis.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban Kinetic analysis Mixed-noncompetitive 2-Chloro-4-nitrophenyl-4-O-β-d-galactopyranosyl-maltoside a-Acarviosinyl- (1 - 4)-a-D-glucopyranosyl-(1 - 6)-D-glucopyranosylidene-spiro-thiohydantoin
Megjelenés:	Biochemical And Biophysical Research Communications. - 334 : 3 (2005), p. 824-828. -
További szerzők:	Zajácz Ágnes Gálné Remenyik Judit (1965-) (kémia tanár, okleveles vegyész) Gyémánt Gyöngyi (1960-) (vegyész)
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
Borító:
Saját polcon:

001-es BibID:	BIBFORM001058
Első szerző:	Zajácz Ágnes
Cím:	Aleppo tannin : structural analysis and salivary amylase inhibition / Ágnes Zajácz, Gyöngyi Gyémánt, Natale Vittori, Lili Kandra
Dátum:	2007
Megjegyzések:	The effectiveness and specificity of a tannin inhibition on human salivary amylase (HSA) catalysed hydrolysis was studied using 2-chloro-4-nitrophenyl 4-O-?-D-galactopyranosyl-?-D-maltoside (GalG2-CNP) and amylose substrates. Aleppo tannin was isolated from the gall nut of Aleppo oak. This tannin is a gallotannin, in which glucose is esterified with gallic acids. This is the first kinetic report, which details the inhibitory effects of this compound on HSA. A mixed non-competitive type inhibition has been observed on both substrates. The extent of inhibition is markedly dependent on the substrate-type. Kinetic constants were calculated from Lineweaver-Burk secondary plots for GalG2-CNP (KEI 0.82 ?g mL-1, KESI 3.3 ?g mL-1). This indicates a 1:1 binding ratio of inhibitor-enzyme and/or inhibitor-enzyme-substrate complex. When amylose was the substrate the binding ratio of inhibitor to enzyme-substrate complex was found to be 2:1, with the binding constants of KEI 17.4 ?g mL-1, KESI 14.9 ?g mL-1, KESI2 9.6 ?g mL-1. Presumably, the tannin inhibitor can bind not only to HSA, but to the amylose substrate, as well. Kinetic data suggest that aleppo tannin is a more efficient amylase inhibitor than the recently studied other tannin with quinic acid core (GalG2-CNP: KEI 9.0 ?g mL-1, KESI 47.9 ?g mL-1).
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban amiláz inhibíció gallotannin szerkezet-analízis
Megjelenés:	Carbohydrate Research. - 342 : 5 (2007), p. 717-723. -
További szerzők:	Vittori, Natale Gyémánt Gyöngyi (1960-) (vegyész) Kandra Lili (1943-) (biokémikus)
Pályázati támogatás:	T047075 OTKA
Internet cím:	Elektronikus változat DOI Szerző által megadott URL
Borító:
Saját polcon: