As part of the “Excellence Initiative – Research University” program, we invite you to a lecture by Professor Francesco Malatesta from the Sapienza University of Rome, Department of Biochemical Sciences, Rome, Italy. The lecture will take place on October 8th at 10:30 a.m. in room 1.03 at the Faculty of Biotechnology of the University of Wrocław.

Title: “Bimolecular reactions unleashed: Beyond pseudo-first order kinetics”
Abstract: In biological systems, kinetic mechanisms predominantly fall into two categories: first-order and second-order reactions. First-order reactions encompass chemical steps in enzyme-catalyzed processes, reaction-coordinate-related conformational changes, and the sequence of elementary conformational transitions guiding a protein to its folded state (or unfolded state). Second-order reactions are equally crucial, governing every enzyme-substrate encounter, protein-ligand interactions, and allosteric interactions. These processes evolve temporally as second-order phenomena, where the rate of reaction is proportional to the concentration of two reactants. Typically, second-order reactions are investigated under pseudo-first-order (PFO) conditions, achieved experimentally by maintaining one reagent in excess relative to the other (so-called 10-fold rule). This approach yields a significant advantage: the reaction’s time course approximates an exponential curve, simplifying analysis and interpretation.

In many experimental situations, the PFO approximation cannot be applied due to constraints such as reagent solubility, availability, or diffusion-controlled reactions. In these cases, comparable concentrations of reactants must be used, necessitating a more general kinetic model. I have developed a comprehensive equation (1) that accurately describes the non-exponential time profiles observed in such situations. This model reveals complex, non-linear behavior of observed rate constants as experimental conditions deviate from PFO conditions, a phenomenon not previously well-described analytically. The broad applicability of this model and its novel insights suggest it could significantly impact the field of chemical kinetics and related areas of study. I will present several examples demonstrating the model’s utility in various experimental scenarios.

Reference: F. Malatesta, The study of bimolecular reactions under non-pseudo-first order conditions. Biophysical Chemistry 116 (2005) 251 – 256.

Professor Francesco Malatesta is an outstanding scientist with numerous achievements.

Scientific achievements:

1. Extensive research on cytochrome c oxidase and other respiratory chain proteins (over 100 publications in prestigious international journals)
2. Development of a novel equation for analyzing second-order reactions, useful for studying electron transfer and protein folding
3. Characterization of terminal oxidases from various bacterial species
4. Structural and functional studies on trypanothione reductase, pyridoxine 5′-phosphate oxidase, and other enzymes with potential pharmaceutical applications
5. Cloning of the phosphodiesterase V gene from bovine lung, relevant to sildenafil research

Teaching achievements:

1. Full Professor of Biological Chemistry at prestigious Italian universities since 1994
2. Coordinator of the Chemistry and Biochemical Propaedeutics course at Sapienza University of Rome since 2009
3. Coordinator of the Biochemistry course in the English Medicine and Surgery Master’s Degree Course at Sapienza University of Rome since 2012
4. Coordinator of the PhD Course in Biochemistry at Sapienza University of Rome (2011 2016)
5. Education Ambassador within the FEBS Education and Training Committee since 2018 and member of the FEBS Education and Training Committee since 2023

Other achievements:

1. Co-author of textbooks on medical chemistry and biochemistry and research papers (e.g. PNAS, JBC, FEBS J, BBA)
2. Organizer of international conferences and courses on protein structure and function.
3. Editor and reviewer for several international biochemistry journals
4. Recipient of numerous research grants
5. Member of prestigious scientific societies (e.g. the Italian Society of Biochemistry and Molecular Biology and the American Society of Biochemistry and Molecular Biology)