Abstract
Pectate lyase (EC 4.2.2.2) catalyzes the cleavage of α-1,4-glycosidic bonds of pectin polymers, and it has potential uses in the textile industry. In this study, a novel pectate lyase belonging to polysaccharide lyase family 10 was screened from the secreted enzyme extract of Paenibacillus polymyxa KF-1 and identified by liquid chromatography-MS/MS. The gene was cloned from P. polymyxa KF-1 genomic DNA and expressed in Escherichia coli. The recombinant enzyme PpPel10a had a predicted Mr of 45.2 kDa and pI of 9.41. Using polygalacturonic acid (PGA) as substrate, the optimal conditions for PpPel10a reaction were determined to be 50 °C and pH 9.0, respectively. The Km, vmax and kcat values of PpPel10a with PGA as substrate were 0.12 g/L, 289 μmol/min/mg, and 202.3 s−1, respectively. Recombinant PpPel10a degraded citrus pectin, producing unsaturated mono- and oligogalacturonic acids. PpPel10a reduced the viscosity of PGA, and weight loss of ramie (Boehmeria nivea) fibers was observed after treatment with the enzyme alone (22.5%) or the enzyme in combination with alkali (26.3%). This enzyme has potential for use in plant fiber processing.
Highlights
Pectin is a heteropolysaccharide mainly composed of α-1,4-linked galacturonic acids with different degrees of esterification [1,2]
Genes encoding pectate lyases have been cloned from Bacillus spp., such as for the pectate lyase from B. tequilensis SV11; PEL168, Apel and rePelB from B. subtilis; BliPelA from B. licheniformis; Bsp165PelA from Bacillus spp
Using citrus pectin as the substrate, the pectate lyase activity accumulated with prolonged cultivation time, up to 36 h (Figure S1)
Summary
Pectin is a heteropolysaccharide mainly composed of α-1,4-linked galacturonic acids with different degrees of esterification [1,2]. Recent studies showed that the degradation products of pectin have good physicochemical properties, and wide application prospects as food additives, pharmaceutical molecules, and materials for cosmetics [4,5]. Pectate lyase has received increasing attention because of its potential applications in various industries, such as in the extraction and clarification of fruit juices and wine, scouring of cotton fabric, retting of flax, degumming of ramie fibers, and treatment of pectic wastewater [7]. The traditional degumming process is performed by alkaline treatment at high temperature, which damages the fibers and causes environmental pollution. Alkaline pectate lyases are preferred for degumming ramie since pectin is more soluble in alkaline solution [12]. The recombinant enzyme was purified, and its ability to remove the pectin from ramie was explored
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