ANALYSIS OF SURFACE BINDING INTERACTION BETWEEN AFLATOXIN B1 AND PEPTIDOGLYCAN IN LACTIC ACID BACTERIA USING MOLECULAR DYNAMICS

• Main Author: Dwi Adiguna, Dimas
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/41727
• Institution: Institut Teknologi Bandung

Efforts to prevent Aflatoxin B1 (AFB1), carsinogenic substance produced as secondary metabolite of Aspergillus flavus and threatening Indonesia’s food safety, in human body are enterosorption and chemosorption. Enterosorption is one of the most potential solution to reduce aflatoxin exposure in situ of human body because it uses sorbent material to absorp targeted molecule and disposed out of body. Lactobacillus, especially some specific strain, are the most effective and safe sorbent material used to conduct enterosorption in human gastrointestinal tract. It uses physical phenomena where mycotoxins such as AFB1 absorped via weak noncovalent bond in its surface, hence called surface binding. Theoretical model of surface binding mechanism has been proposed by Bueno et. al. (2007) using Langmuir isotherm adsorption model, but limitation in experimental approach has not been able to strongly conclude which cell wall constituent has critical role in surface binding. In this research, interaction between AFB1 and peptidoglycan, as major constituent in lactic acid bacteria cell wall, is analyzed using molecular dynamics with umbrella sampling as enhanced sampling technique. Weighted histogram analysis has been conducted from 22 sampling windows in 3,5 nm surface separation distance perpendicular to peptidoglycan orientation as its reaction coordinate. Interaction free energy (?????????????????????) calculated from this research is -26,39 kJ.mol-1. Langmuir constants calculated from simulation is 2,79 x 104 site-1 and shows a good agreement with experimental results. Parameters used in umbrella sampling have been compared with validation equiation from Kastner and Thiel (2006) and satisfy its validity range.