Chemistry December 2003 Vol 52/4 []

CONTENTS & ABSTRACTS

InEnglish. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.

Chemistry



Volume 52 No. 4December 2003



Compositionof the essential oil of dill, celery, and parsley from Estonia;147–154

Anne Orav, Tiiu Kailas, and Anna Jegorova

Abstract. The qualitative and quantitative composition ofthe essential oil of dill, celery, and parsley growing in Estonia was studiedusing the simultaneous distillation/extraction micro-method for oil isolationand capillary gas chromatography for analysing the extracts. The yields of theoils from dried aromatic plants after two hours distillation were2.9–4.3 mg/g. Forty-eight compounds were identified representing over 96%of the total oil. α-Phellandrene (75.1–75.8%), β-phellandrene (7.4–7.9%),dill ether (2.2–3.9%), and limonene (2.8–2.9%) were the principal components ofdill oil. p-1,3,8-Menthatriene (40.0–44.6%), β-phellandrene(15.1–16.9%), myristicin (13.0–13.1%), and myrcene (6.5–7.0%) werecharacteristic constituents in oil from parsley leaves, but apiole (34.5%),myristicin (28.8%), and terpinolene (13.2%) predominated in parsley root oil.Celery oil contained in high quantities limonene (62.4–70.3%),(Z)-β-ocimene (10.1–10.5%), and phthalide isomers (total 13.4–16.6%). Dryingof aromatic plants for four weeks at room temperature did not significantlychange the chemical composition of their essential oil.

Key words: Anethum graveolens, Petroselinumcrispum, Apium graveolens, Apiaceae,essential oil composition, effect of drying.

Purificationof resveratrol from vine stems; 155–164

Aavo Aaviksaar, Mati Haga, Tõnu Püssa, Mati Roasto, and George Tsoupras

Abstract. A modified method forpreparative purification of trans-resveratrol(trans-3,4¢,5-tri­hydroxystilbene) from vine stems is presented. It includestwo new procedures added to the known scheme of resveratrol separation fromligneous organs of vine by ethanol–water extraction: (1) treat­ment ofethanolic solution of vine stem stilbenoid extract with diethyl ether forprecipitation of a dark brown matter from the extract; (2) preparativecolumn chromatography on polyamide carrier for separation of resveratrol from thecrude ethanolic extract. As a result, 93.8% resveratrol concentrate with 0.7%of its dimer viniferin impurity was obtained. Resveratrol and viniferincontents in the stems of various frost-hardy hybride cultivars of Vitis vinifera grown open air in Estonia(‘Hasaine Sladki’, ‘Jubilei Novgoroda’, Vitisvinifera cv., ‘ES 12-7-98’, ‘Marechal Joffre’, ‘Zilga’) were determined forthe plant material collected in July and in October. Lignified stems collectedin October turned out to be an excellent source for producing vine stemstilbenoid (resveratrol and viniferin) concentrates for use as healthyingredients in functional food for preventing heart diseases andatherosclerosis.

Key words: resveratrol,stilbenoids, viniferin, vine stems, Vitisvinifera.

Steady-statekinetic analysis of protein kinase A interaction with peptide and ATP;165–177

Aleksei Kuznetsov, Nikita Oskolkov,Mats Hansen, and Jaak Järv

Abstract. Kinetics of Kemptide (LRRASLG) phosphorylation by protein kinase A(E.C.2.7.1.37) was studied in a wide ATP and peptide concentration interval anda simple procedure was proposed to characterize the interaction of these twosubstrates with the enzyme active centre. The kinetic analysis was made understeady-state conditions and was based on the assumption of the random-ordermechanism of binding of the two substrates. Inhibition of the reaction byexcess of ATP was observed and considered in data processing. A procedure wasdesigned for analysis of the interaction mechanism of protein kinase reversibleinhibitors with the enzyme proceeding from the steady-state kinetic data.

Key words: proteinkinase A, peptide phosphorylation, kinetic mechanism, bi-substrate reaction.

Kineticmodel for protein kinase simultaneous interaction with peptide, ATP, andbi-functional inhibitor; 178–187

Aleksei Kuznetsov, Heli Väärtnõu-Järv, and Jaak Järv

Abstract. A kinetic model for protein kinase inhibition by bi-functionalinhibitors, resembling the bi-substrate–enzyme complex and interacting withboth ATP and peptide binding sites in the enzyme active centre, was analysed.The model provides a possibility for analysis of the enzyme–ligand interactionson the basis of the second-order rate constants, calculated from thesteady-state kinetic data of the protein kinase catalysed phosphorylationreaction. The experimental data should be obtained at a wide range of peptide,ATP, and the bi-functional inhibitor concentration. The kinetic equations allowcharacterization of the enzyme–substrate–inhibitor ternary complexes as well asthe enzyme–inhibitor binary complex by the appropriate kinetic parameters. Adata processing algorithm is proposed for their calculation. The results can beuseful for understanding the inhibition mechanism, including the possibilitiesof simultaneous interaction of substrates and inhibitor in the active centre.This information is important for designing new inhibitors.

Key words: protein kinase A, peptide phosphorylation, bi-functional inhibitor,kinetic mechanism, steady-state kinetics.

Instructions to authors; 188–190

Contents of volume 52; 191–192