Phosphorylation of Cotton Cellulose with Baker’s Yeast Hexokinase Tzanko Tzanov, Maria Stamenova, Artur Cavaco-Paulo* Departamento de Engenharia Te ˆxtil, Universidade do Minho, Campus de Azure ´m, 4800-058 Guimara ˜es, Portugal Fax: þ351 253 510293; E-mail: artur@det.uminho.pt Keywords: enzymes; hexokinases; functionalization of polymers Introduction The chemical modification of cotton cellulose, by introduc- ing new functional groups or compounds, could be a way to improve dye fixation, water and soil-repellence, crease- resistance, handle, flame retardance and others. Hexokinase enzymes (EC 2.7.1.1.) catalyze phosphoryl transfer from adenosine-5 0 -triphosphate (ATP) [1–4] to the 6-hydroxyl group of a number of furanose and pyranose compounds. [5] The ability of hexokinase to initiate the transfer of phos- phate groups suggested the application of this enzyme to the functional modification of the C6-hydroxyl groups in cellulose. Chemical phosphorylation usually is a rather complicated process, requiring several protection and de- protection steps. [6,7] Enzymatic phosphorylation can make the synthesis more efficient, eliminating many of these steps. The introduction of phosphate groups into cellulose will provide a polymer highly reactive toward various chemical compounds. Experimental Part Bleached, twill weave, 120 g  m 2 , 100% cotton fabric was used. The enzymatic phosphorylation of the samples was carried out at 30 8C in an Ahiba Spectradye-Datacolor dyeing apparatus with closed vessels, at 40 r.p.m. for 6 h, with 40 U  mL 1 hexokinase (EC 2.7.1.1., Type IV: from baker’s yeast, Sigma; one unit will phosphorylate 1 mmol of D-glucose per min at pH 7.6 at 25 8C) dissolved in 50 mmol potassium phosphate buffer (pH 7.6) and 50 mmol of a solution of ATP in deionized water, disodium salt (Sigma), using a liquor to fabric ratio of 20:1. Fabrics were first treated with the ATP solution for 15 min to ensure the impregnation of the textile material, and then the enzyme was added. After completing the process the enzymatically treated fabrics were washed under reflux to remove any residual protein. Sigma procedure No. 345-UV for quantitative, ultraviolet, kinetic determination of glucose-6-phosphate dehydrogenase (G-6-PDH, EC 1.1.1.49) in blood at 340 nm, was adopted for the detection of glucose-6-phosphate (G-6-P) formed in the hexokinase phosphorylation reaction. G-6-PDH is an enzyme that catalyzes the first step in the pentose phosphate shunt, oxidizing glucose-6-phosphate to 6-phosphogluconate (6-PG) and reducing nicotinamide adenine dinucleotide phosphate (NADP) to NADPH, according to Equation (1): G-6-P þ NADP þ ! G-6-PDH 6-PG þ NADPH þ H þ ð1Þ NADP is reduced by G-6-PDH in the presence of G-6-P. The rate of formation of NADPH (measured spectrophoto- metrically following the increase in absorbance at 340 nm) is proportional to the G-6-PDH activity and thus to the Communication: Here we report for the first time on phos- phorylation of cotton cellulose using baker’s yeast hexokinase and phosphoryl donor adenosine-5 0 -triphosphate. An enzy- matic assay was adopted for determination of the degree of phosphorylation of cellulose. This functional modification of cellulose resulted in improved colorability and flame resistance. Phosphorylated glucopyranose unit of cellulose. 962 Macromol. Rapid Commun. 2002, 23, 962–964 Macromol. Rapid Commun. 2002, 23, No. 16 ß WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2002 1022-1336/2002/1611–962$17.50þ.50/0