Journal of applied Science and Technology Vol 9, No. 1, December 2013, pp 1-7 ISSN 2218-841X A Computational Study on 3-Hydroxy-3-Methylglutaryl-CoA Reductase in Lactobacillus spp. Utpal Kumar Adhikari 1 , Kamrul Islam 1 , Tammana Ferdous 1 , Zannatul Nyme 1 , Md.Sazzad Hossain 2 , Abul Kalam Azad 1 ,Shamima Nasrin Sima 3 , Nilufa Akther Banu 1 and M. Mizanur Rahman 1 * 1 Department of Biotechnology and Genetic Engineering, Islamic University, Kushtia-7003, Bangladesh. 2 Department of Statistics, Islamic University, Kushtia-7003, Bangladesh. 3 Department of Botany, Rajshahi University, Rajshahi, Bangladesh. *Corresponding author:M. Mizanur Rahman, E-mail: mmrahmanbtg79@hotmail.com (Received 30 June 2014; Accepted 26 July 2014) ABSTRACT The enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase catalyzes the conversion of HMG-CoA to mevalonate, a four-electron oxidoreduction that is the rate-limiting step in the synthesis of cholesterol and other isoprenoids. Six Lactobacillus spp. were used to screen and determine the amino acid composition of HMG-CoA reductase sequence. The sequence of HMG-CoA reductase was retrieved from BRENDA. Multiple sequence alignment and phylogeny tree was constructed by ClustalW and phylogeny.fr, respectively. Secondary structure and amino acid composition of HMG-CoA were determined by NetSurfp and ProtParam. The essential amino acid composition of HMG-CoA reductase was high percentage (48.4%) in the Lactobacillus sanfranciscensis and less (45.2%) in Lactobacillus delbrueckii. The Multiple sequence alignment showed the highest similarity (99.77%) between Lactobacillus paracasei and Lactobacillus casei and less similarity (27.45%) between Lactobacillus paracasei and Lactobacillus delbrueckii. The result concluded that Lactobacillus sanfranciscensis will be good source of HMG-CoA reductase that will be useful to produce target drug for the reduction of cholesterol and other isoprenoids of human. Keywords: HMG-CoA reductase; multiple sequence alignment; phylogeny tree; cholesterol; Lactobacillus spp. INTRODUCTION 3-Hydroxy-3-methylglutaryl–coenzyme A (HMG-CoA) reductase inhibitors, also known as statins, act on the rate- limiting step in the mevalonate pathway by which HMG- CoA is converted to mevalonate 1 . Statins reduce other by- products of the mevalonate pathway (MetaCyc mevalonate pathway), including ubiquinone, sterol, dolichol and the isoprenoids farnesyl pyrophosphate and geranylgeranylpyrophosphate. Statins decreased cholesterol production leads to an increase in the number of LDL membrane receptors, which increases clearance of LDL cholesterol from blood circulation. Quantitative summary showed that, treatment with statins reduce overall stroke incidence by 30%, owing to a reduction in non-fatal stroke 2 and also have anti- inflammatory properties 3 . Therapy with statins reduces total mortality in men with hypercholesterolemia when used for both primary and secondary prevention of coronary artery disease. Statins are also used to lower serum cholesterol as a means of reducing the risk of cardiovascular disease 4,5 . In humans, the gene for HMG- CoA reductase is located on the long arm of the fifth chromosome (5q13.3-14) 6 . Related enzymes having the same function are also present in other animals, plants and bacteria. Lactobacillus, also called Doderlein's bacillus, is a genus of gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria 7 . Some species of Lactobacillus contain HMG-CoA reductase which is enriched with 1