JOURNAL OF OIL PALM RESEARCH 24 (AUGUST 2012) 1432 BIOCHEMICAL STUDIES AND PURIFICATION OF OIL PALM (Elaeis guineensis Jacq.) -KETOACYL-ACYL-CARRIER-PROTEIN (ACP) SYNTHASE (KAS) II ENZYME UMI SALAMAH RAMLI*; MOHAMMED NOOR EMBI**; OTHMAN OMAR** and RAVIGADEVI SAMBANTHAMURTHI*; ABSTRACT The rapid increase in palm oil production over the last 20 years has made this oil the most important in the world. Palm oil produced in the mesocarp of the oil palm (Elaeis guineensis) fruit contains primarily palmitic (44%) and oleic (39%) acids with only a small proportion of polyunsaturated fatty acids. As a prelude to detailed biochemical analysis of the fatty acid biosynthesis of oil palm, we examined β-ketoacyl-ACP synthase (KAS) II activity, and evidence is presented on its importance in palmitic acid accumulation. In this study, three different oil palm breeding materials were screened for KAS II and fatty acid compositions. Collectively, the results strongly suggest that KAS II plays an important role in determining the relative amounts of C16 and C18 fatty acids in oil palm. KAS II activity was profled through various stages of fruit development from 12 to 22 weeks after anthesis (WAA). The data depicted a pattern of progressive increase in KAS II activity similar to that of triacylglycerol synthesis in the oil palm mesocarp which started at 15 WAA and reached a maximum around 20 WAA. The enzyme was purifed to homogeneity (>9000-fold purifcation) using a combination of ion exchange on CM-Sepharose, HR-DEAE, hyroxyapatite and affnity chromatography (ACP-Sepharose). Activity of the purifed enzyme was inhibited by the chelating agent ethylene diamine tetra-acetate (EDTA) (1 M), but the inhibitory action could be overcome by divalent cations such as Mn 2+ or Mg 2+ (10 mM). Optimal activity was observed at pH 4.5. The data represent the frst contribution to the biochemical characterisation of oil palm KAS II activity associated with fatty acid biosynthesis. * Malaysian Palm Oil Board, P. O. Box 10620, 50720 Kuala Lumpur, Malaysia. E-mail: umi@mpob.gov.my ** Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43650 UKM Bangi, Selangor, Malaysia. oil, accounting for approximately 86% of total production. The mesocarp of the ripe oil palm fruit accumulates large amounts of oil which contains palmitic acid (C16:0) at up to 44% of the total fatty acids. Other major fatty acids in palm oil include oleic and stearic acids which account for 39% and up to 5% of the total composition, respectively (Tan and Oh, 1981). Palm oil tends to feed into relatively low-value generic commodity streams, whether for food or oleochemical use (Murphy, 2009). New palm oil tailored for specifc markets would thus have value-addition and would compete more effectively to meet the demands from the expanding oil business and changing market requirements. INTRODUCTION Oil palm (Elaeis guineensis Jacq.) is now the world’s most important edible oil when ranked by global production and consumption. Malaysia and Indonesia produce most of the world’s palm Keywords: oil palm (Elaeis guineensis), β-ketoacyl-acyl-carrier-protein (ACP) synthase (KAS) II, enzyme purifcation, fatty acid biosynthesis. Date received: 2 June 2011; Sent for revision: 15 June 2011; Received in final form: 16 December 2011; Accepted: 15 May 2012. Journal of Oil Palm Research Vol. 24 August 2012 p. 1432-1441 L-Umi Salamah.indd 1432 8/2/12 10:07 AM