Archives: Projekti

IMI projekti

Biomedical Research of Reproduction and Development

The Ministry of Science, Education and Sports of the Republic of Croatia (2002-2006)

Collaborative project at the University of Zagreb School of Medicine

Coordinator: Davor Ježek, Medical School Zagreb;
Principal investigators at the Institute: Martina Piasek, Aleksandra Fučić (2003-2004).

Mechanism of Interaction of Esterases with Organophosphates

The Ministry of Science, Education and Sports of the Republic of Croatia (2002-2006)

Principal Investigator: Vera Simeon
Since January 1 2005, Principal Investigator Zrinka Kovarik

SUMMARY
This project deals with interactions of esterases and organophosphates (triesters of phosphorus acids), and other inhibitors and substrates. Some nerve warfare agents and pesticides are organophosphates (OP). Three esterases will be studied: acetylcholinesterase (AChE, EC 3.1.1.7), butyrylcholinesterase (BChE, EC 3.1.1.8) and a phosphoric triester hydrolase, paraoxonase (EC 3.1.8.1).

Organophosphates inhibit serine esterases, AChE and BChE, but some of these compounds are substrates of paraoxonase. AChE has a vital function to terminate cholinergic neurotransmission by rapid hydrolysis of acetylcholine. Phosphorylation of the active site of this enzyme is the main cause of OP toxicity.

BChE is also phosphorylated by OP but has no obvious physiological function. Therefore this enzyme acts as a scavenger of OP and of some other esters (pesticides and drugs). Phosphoric triester hydrolases break down OP to non-toxic products thus playing an important role in detoxication. Our studies are focused on stereospecificity of AChE and BchE, and on the role of amino acid residues in their active site gorge.

The source of enzymes will be DNA-derived enzymes, native and purified preparations. The project comprises interactions with substrates, symmetric and chiral inhibitors: organophosphates, esters of carbamic acids, phenotiazine and quinuclidine derivatives. Kinetic constants of interactions of the enzymes with substrates, inhibitors and reactivators will be determined. Several kinetic models will be evaluated on obtained experimental data. Standardisation of the enzyme activity measurements and determination of phenotypes of BChE and paraoxonase in human blood are parts of the programme. Conventional (spectrophotometry and pH-stat titration) and stopped-flow techniques will be used for measuring the enzyme activities.

Mechanisms of Heavy Metal Toxicity in Kidney and Reproductive Tract

The Ministry of Science, Education and Sports of the Republic of Croatia (2002-2006)

Principal Investigator: Ivan Sabolić

Project funded since: July 1, 2002
Duration: 3 years

SUMMARY
Aiming to understand in more details the mechanisms of toxicity of some heavy metals (Cd, Hg, Pb, cis-Pt) in the mammalian renal and reproductive tract epithelium, we perform studies in experimental animals (rats) in which we use various preparative, functional, immunocytochemical, and molecular biology methods to investigate the time-dependent effects of heavy metals upon cell cytoskeleton and specific mRNA’s as well as the activity and distribution of various transporters in cells along the nephron and male and female reproductive tract.

We expect to see an early (within hours following heavy metal application) damage of cytoskeleton, an abnormal distribution of the cell membrane transporters, and impaired cell functions, however with no change in the specific mRNA’s abundance.