131 Science Highlights - Thematic Area 3 | 5 ARGINASE KINETIC CHARACTERIZATION OF THE GASTROPOD Nacella concinna AND ITS PHYSIOLOGICAL RELATION WITH ENERGY REQUIREMENT DEMAND AND THE PRESENCE OF HEAVY METALS Edson Rodrigues 1,* ,Helena Passeri Lavrado 2 , Lucélia Donatti, Cecília N. K. Suda 1 , Edson Rodrigues Júnior 3 , Mariana Feijó de Oliveira 1 , Gannabathula Sree Vani 1 1 Departamento de Biologia, Instituto Básico de Biociências, Universidade de Taubaté – UNITAU, Campus do Bom Conselho, Taubaté, SP, Brazil 2 Departamento de Biologia Marinha, Universidade Federal do Rio de Janeiro – UFRJ, Rio de Janeiro, RJ, Brazil 3 Programa de Pós-graduação em Biologia Molecular e Celular, Centro Politécnico, Universidade Federal do Paraná – UFPR, Curitiba, PR, Brazil *e-mail: rodedson@gmail.com Abstract: Arginases are metalloenzymes broadly distributed in nature. Tese enzymes catalyze the L-arginine hydrolyses to L-ornithine and urea. Te aim of the present work is to determine the tissue levels of arginase, its kinetic properties and subcellular localization. In December 2009, specimens were collected in Admiralty Bay, King George Island near the Brazilian Research Station. Te argininolytic specifc activity of foot muscle, gills and pool of other tissues was 87.0 ± 15.1; 9.8 ± 1.8 and 3.8 ± 1.0 mU/mg protein, respectively. Mainly localized in the cytosol, gills and muscular arginase Km values for L-arginine were 57.0 ± 10.5 and 66.2 ± 14.6 mM, respectively. High arginase levels in gills could be related to the systemic control of L-arginine concentrations, which is vital for energetic metabolism of phospho-L-arginine and of polyamines in the control of cell proliferation though the probable physiologic metal cation is Mn 2+ , some arginases are activated by Co 2+ and Ni 2+ . Te muscle Nacella concinna arginases were activated by Mn 2+ and Co 2+ and inhibited by Cd 2+ whereas; gills arginase was activated only by Mn 2+ and inhibited by Cd 2+ and Zn 2+ . Keywords: Antarctica, arginase, Nacella concinna, heavy metal Introduction The organisms that inhabit the intertidal zone on the coasts of the Antarctic Peninsula and adjacent Islands are periodically exposed to the thermal regime of the terrestrial environment as well as summer melt waters. Te melt water creates micro environments with low salinity and elevated levels of heavy metals derived from lithogenic sources (Ahn et al. 1999, 2002). In addition, microphytobenthos are considered the principal food source and are also an important natural source of heavy metals, particularly Cd 2+ (Ahn et al., 2004; Keil et al., 2008). Intertidal zones are also most vulnerable to anthropogenic pollutants. Te gastropod Nacella concinna, is the most conspicuous macro invertebrate in the Antarctic intertidal zone, which has been used in the biomonitoring, for example in the diesel fuel spill from the vessel, Bahia Paradise, in Arthur Harbour (Kennicutt II & Sweet, 1992). Arginases are metalloenzymes that need a divalent cation to attain maximum activity. Te probable physiological http://dx.doi.org/10.4322/apa.2014.037