alpha-l-Arabinofuranosidases (alpha-l-Abfases, EC 3.2.1.55) display a broad specificity against distinct glycosyl moieties in branched hemicellulose and recent studies have demonstrated their synergistic use with cellulases and xylanases for biotechnological processes involving plant biomass degradation. In this study, we examined the structural organization of the arabinofuranosidase (GH51 family) from the mesophilic Bacillus subtilis (AbfA) and its implications on function and stability. The recombinant AbfA showed to be active over a broad temperature range with the maximum activity between 35 and 50 A degrees C, which is desirable for industrial applications. Functional studies demonstrated that AbfA preferentially cleaves debranched or linear arabinan and is an exo-acting enzyme producing arabinose from arabinoheptaose. The enzyme has a canonical circular dichroism spectrum of alpha/beta proteins and exhibits a hexameric quaternary structure in solution, as expected for GH51 members. Thermal denaturation experiments indicated a melting temperature of 53.5 A degrees C, which is in agreement with the temperature-activity curves. The mechanisms associated with the unfolding process were investigated through molecular dynamics simulations evidencing an important contribution of the quaternary arrangement in the stabilization of the beta-sandwich accessory domain and other regions involved in the formation of the catalytic interface of hexameric Abfases belonging to GH51 family.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Ctr Nacl Pesquisa Energia & Mat, Lab Nacl Ciencia & Tecnol Bioetanol, BR-13083970 Campinas, SP, BrazilUniv Estadual Campinas UNICAMP, Campinas, SP, BrazilUniv Estadual Paulista IBILCE UNESP, Inst Biociencias Letras & Ciencias Exatas, Dept Fis, Sao Jose Do Rio Preto, SP, BrazilUNESP Botucatu, Inst Biociencias, Dept Fis & Biofis, Botucatu, SP, BrazilLab Nacl Biociencias LNBio CNPEM, Campinas, SP, BrazilUniv Estadual Paulista IBILCE UNESP, Inst Biociencias Letras & Ciencias Exatas, Dept Fis, Sao Jose Do Rio Preto, SP, BrazilUNESP Botucatu, Inst Biociencias, Dept Fis & Biofis, Botucatu, SP, BrazilFAPESP: 08/58037-9FAPESP: 10/51890-8FAPESP: 11/14200-6FAPESP: 11/13242-7FAPESP: 10/11499-1CNPq: 133394/2011-5CNPq: 475022/2011-4CNPq: 310177/2011-1CNPq: 2011/17658-3CNPq: 140420/2009-6