Találati lista | Tudóstér

001-es BibID:	BIBFORM052157
Első szerző:	Fazekas Erika (kémikus)
Cím:	Unexpected mode of action of sweet potato β-amylase on maltooligomer substrates / Erika Fazekas, Katalin Szabó, Lili Kandra, Gyöngyi Gyémánt
Dátum:	2013
ISSN:	1570-9639
Megjegyzések:	β-Amylase (EC 3.2.1.2), one of the main protein of the sweet potato, is an exo-working enzyme catalyzing the hydrolysis of α(1,4) glycosidic linkages in polysaccharides and removes successively maltose units from the non-reducing ends. The enzyme belongs to glycoside hydrolase GH14 family and inverts the anomeric configuration of the hydrolysis product. Multiple attack or processivity is an important property of polymer active enzymes and there is still limited information about the processivity of carbohydrate active enzymes. Action pattern and kinetic measurements of sweet potato β-amylase were made on a series of aromatic chromophor group-containing substrates (degree of polymerization DP 3-13) using HPLC method. Measured catalytic efficiencies increased with increasing DP of the substrates. Processive cleavage was observed on all substrates except the shortest pentamer. The mean number of steps without dissociation of enzyme-product complex increases with DP of substrate and reached 3.3 in case of CNPG11 indicating that processivity on longer substrates was more significant. A unique transglycosylation was observed on those substrates, which suffer processive cleavage and the substrates were re-built by the enzyme. Our results are the first presentation of a transglycosylation during an inverting glycosidase catalyzed hydrolysis. The yield of transglycosylation was remarkable high as shown in the change of the CNPG11 quantity. The CNPG11 concentration was doubled (from 0.24 to 0.54 mM) in the early phase of the reaction.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban β-Amylase Sweet potato Processive action Maltooligomers HPLC action pattern Transglycosylation
Megjelenés:	Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics. - 1834 : 10 (2013), p. 1976-1981. -
További szerzők:	Szabó Erzsébet Katalin (1989-) (vegyész) Kandra Lili (1943-) (biokémikus) Gyémánt Gyöngyi (1960-) (vegyész)
Pályázati támogatás:	TÁMOP-4.2.1/B-09/1/KONV-2010-0007 TÁMOP Szénhidrát anyagcserében szerepet játszó enzimek tanulmányozása
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
Borító:
Saját polcon:

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: