VIEW ARTICLE    http://dx.doi.org/10.1094/ASBCJ-2013-0103-01

Ascorbate Peroxidase in Malted Barley (1). Makoto Kanauchi, Department of Food Management, Miyagi University, 2-2-1 Hatatate Taihaku-ku Sendai Miyagi, 982-0215, Japan; and Charles W. Bamforth (2), Department of Food Science & Technology, University of California, Davis, CA 95616-8598. (1) A preliminary report of this work was made at the World Brewing Congress, Portland, OR, July/August 2012. (2) Corresponding author. E-mail: <cwbamforth@ucdavis.edu>; phone: +1-530-752-9476; fax: +1-530-752-4759. J. Am. Soc. Brew. Chem. 71(2):97-102, 2013.

An ascorbate peroxidase has been identified in the acrospire and aleurone of germinating barley. Its synthesis is triggered in the aleurone by the presence of ascorbic acid and hydrogen peroxide. It has a relative molecular weight of 23,000–26,000 and a broad pH optimum, with 70% minimum of maximal activity over the pH range 5–7. However, it is relatively sensitive to heat, losing 50% of its activity in 30 minutes at 40°C. The enzyme has a very high affinity for hydrogen peroxide. Keywords: Acrospire, Aleurone, Ascorbic acid, Hydrogen peroxide, Peroxidase

Un ascorbato peroxidasa ha sido identificado en la plúmula y aleurona de la cebada germinada. Su síntesis es activada en la aleurona por la presencia de ácido ascórbico y peróxido de hidrógeno. Tiene un peso molecular relativo de 23,000-26,000 y un óptimo de pH amplio, con un 70% mínimo de actividad máxima en el intervalo de pH 5–7. Sin embargo, es relativamente susceptible al calor, perdiendo 50% de su actividad en 30 minutos a 40°C. La enzima tiene una afinidad muy alta para el peróxido de hidrógeno. Palabras claves: Ácido ascórbico, Aleurona, Peroxidasa, Peróxido de hidrógeno, Plúmula