N = 3).Lau et al. BMC Complementary and Alternative Medicine 2013, 13:313 http://biomedcentral/1472-6882/13/Page 9 ofInhibition pattern of ACE inhibitorsPeptide AHEPVK exhibited by far the most potent ACE inhibitory activity (IC50 62.8 M) and it shows stability against gastrointestinal digestion. Thus, it was chosen to figure out its inhibition pattern against the ACE enzyme. In accordance with the Lineweaver-Burk plot in Figure six, peptide AHEPVK showed a competitive inhibition pattern against the ACE. This suggests that the peptide may bind towards the active website of ACE to block it from binding towards the substrate. Additionally, ACE has been reported to show preference for competitive inhibitors that contain a hydrophobic amino acid in the third position from the C-terminal [44,45]. This is in accordance using the amino acid sequence of AHEPVK which might clarify the competitive inhibition pattern exhibited by this peptide. The competitive inhibition pattern exhibited by AHEPVK is similar to ACE inhibitory cIAP-1 Inhibitor review peptides purified from the edible mushrooms G. frondosa, P. cornucopiae, P. adiposa and T. giganteum [18-21]. Furthermore, a commercial ACE inhibitor and antihypertensive drug, captopril, also inhibits ACE within a competitive manner .Received: 19 March 2013 Accepted: 6 November 2013 Published: 11 NovemberConclusion In the present study, peptides isolated from P. cystidiosus had been shown to become potential ACE inhibitors. Peptide AHEPVK exhibited a high IC50 worth (62.eight M) and its peptide sequence remained stable following gastrointestinal digestion. It exhibited a competitive inhibition pattern against ACE. Peptide GPSMR was predicted to release a dipeptide ACE inhibitor, GP, from its precursor right after gastrointestinal digestion. Despite the fact that these peptides had decrease ACE inhibitory activity in comparison with commercial antihypertensive drugs, they are derived from food sources and ought to have no unwanted side effects.Abbreviations ACE: Angiotensin I-converting enzyme; RPHPLC: Reverse phase high performance liquid chromatography; SEC: Size exclusion chromatography; LC-MS/MS: Liquid chromatography mass spectrometry. Competing interests The authors declare that they have no competing interests. Authors’ contributions CCL carried out all of the experimentation, analysis of data and drafting in the manuscript. NA involved in monitoring and coordinating the work on mushroom biology and antihypertensive activity. ASS involved in coordinating the function on isolation and purification of peptides; and proteomic analysis. All authors study and approved the final manuscript. Acknowledgements The authors would prefer to thank the University of Malaya (Grant PPP: PS238/ 2008C, PS478/2010B, PV073-2011B) along with the Ministry of Greater Education Malaysia (HIR-MOHE: F000002-21001) for financial assistance for this project. Author particulars 1 Mushroom Research Centre, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. BRaf Inhibitor Molecular Weight 2Medical Biotechnology Laboratory, University of Malaya Centre for Proteomics Study (UMCPR), Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia.References 1. van Vark LC, Bertrand M, Akkerhuis KM, Brugts JJ, Fox K, Mourad J-J, Boersma E: Angiotensin-converting enzyme inhibitors lessen mortality in hypertension: a meta-analysis of randomized clinical trials of renin-angiotensin-aldosterone method inhibitors involving 158 998 patients. Eur Heart J 2012, 33:2088097. 2. Erd EG: The ACE and I: how ACE inhibitors came to be.