Involved in the degradation of arabinan and is a key enzyme in the complete degradation of the plant cell wall. Catalyzes only the cleavage of terminal alpha-(1->5) arabinofuranosyl bonds of arabinan present in the arabinofuranosyl polysaccharides or oligosaccharides. It cannot act on other arabinose-containing polysaccharides and arabinoxylo-oligosaccharides. Hydrolysis of terminal non-reducing alpha-L-arabinofuranoside residues in alpha-L-arabinosides. Optimum pH is 7.0. The enzyme is slowly inactivated above pH 9 and below pH 5. Optimum temperature is 50 degrees Celsius. The enzyme is inactivated at temperatures above 40 degrees Celsius. Glycan metabolism; L-arabinan degradation. Predicted to be exported by the Tat system. The position of the signal peptide cleavage has been experimentally proven. Belongs to the glycosyl hydrolase 43 family.