Lipoxygenase from Banana Leaf:  Purification and Characterization of an Enzyme That Catalyzes Linoleic Acid Oxygenation at the 9-Position

Abstract

The objective of the present study was to purify and characterize the lipoxygenase (LOX) from banana leaf (Giant Cavendishii, AAA), an unutilized bioresource. LOX was extracted, isolated, and purified 327-fold using 25-50% saturation of ammonium sulfate fractionation, hydroxyapatite column separation, and gel filtration on Superdex 200. The molecular mass of the purified LOX was 85 kDa, K(m) was 0.15 mM, and V(max) was 2.4 microM/min.mg using linoleic acid as substrate. Triton X-100 was required in the extraction medium; otherwise, no LOX activity was detected. LOX activity increased with the concentration of Triton X-100 with an optimum at 0.1%. The optimal pH of the purified LOX from banana leaf was 6.2, and optimal temperature was 40 degrees C. The LOX showed the highest reactivity toward 18:2 followed by 18:3 and 20:4. A very low reaction rate was observed toward 20:5 and 22:6. On the basis of retention time in normal phase HPLC, the products of 18:2 or 18:3 catalyzed by purified LOX were hydroperoxyoctadecadienoic acid or hydroperoxyoctadecatrienoic acid. It seems that 9-LOX is the predominant enzyme in banana leaf. Banada leaf dried at 110 degrees C for 2 h developed algal aroma. Banana leaf extract stored at 10 degrees C for 12 h formed an oolong tea-like flavor. Banana leaf extract reacted with 18:2 or soybean oil pretreated with bacterial lipase produced green and melon-like aroma, whereas the same reaction with 18:3 produced a sweet, fruity, cucumber-like flavor note.

Purification and properties of lipoxygenase from opium poppy seedlings(Papaver somniferum L.)

“…The K m value of purified opium poppy LOX determined using linoleic acid as a substrate was similar to the K m value of soluble LOX from tomato fruits (Suurmeijer et al, 1998). The K m value of LOX from pea seeds was 0.44 mM (Szymanowska et al, 2009) and was 0.15 mM in LOX purified from banana leaves (Kuo et al, 2006) and soluble LOX from chicory (Daglia et al, 2005). Other plant LOXs display K m values in the lower micromolar range (Fornaroli et al, 1999;Lorenzi et al, 2006;Sellhorn et al, 2011).…”

Two isoforms of lipoxygenase from mature grains of pearl millet [Pennisetum glaucum (L.) R. Br.]: purification and physico-chemico-kinetic characterization

“…The monomeric nature of LOX was in accordance with LOX extracted from germinating barley (Yang et al 1993), durum wheat endosperm (Hsieh and McDonald, 1984), ungerminating barley (Peter et al 1991), wheat germ (Shiiba et al 1991), durum wheat semolina (Barone et al 1999), tomato (Catherine et al 1998), Cichorium intybus (Daglia et al 2005), rice (Ratachatachaiyos and Theerakulkait, 2009) and Pleurotus ostreatus (Abdullah et al 2014). The molecular mass of purified LOX from banana leaf was 85 kDa (Kuo et al 2006). According to Babitha et al (2004), LOX isozymes in pearl millet seedlings had molecular mass 83, 77 and 73 kDa for LOX 1, 3 and 6, respectively.…”

Banana by-products: an under-utilized renewable food biomass with great potential

“…Biogeneration of aldehydes and alcohols used in the flavor industry can be carried out naturally through enzymatic pathways utilizing enzymes such as lipase, alcohol dehydrogenase (ADH), lipooxygenase (LOX), hydroperoxide lyase (HPLS) (Gigot et al 2010). Kuo et al (2006) reported that banana leaves (Musa cv. Cavendish) contains a membrane-bound enzyme of 9-LOX, which is able to produce oolong tea-like, melonlike, and fruity cucumber-like flavor upon pickling or when treated with soybean oil, linoleic acid, linolenic acid and respectively; the kinetic properties were comparable to LOX obtained from canola seed and English pea.…”

“…Numerous studies have been done to improve the usage of banana by-products to meet the escalating demand of raw materials supply in various industries (Clarke et al 2008;Doran et al 2005;Emaga et al 2008a;Kuo et al 2006). These researches paved new and alternative ways in creating new products and applications with value added approach at the cost of recycling banana agricultural wastes.…”