Alpha-agarase. Hydrolyzes agarose, agarohexaose, neoagarohexaose and porphyran. Hydrolysis of porphyran by this enzyme improves its antioxidant activity. Does not hydrolyze kappa-carrageenan, iota-carrageenen or lambda-carrageenan. Endohydrolysis of 1,3-alpha-L-galactosidic linkages in agarose, yielding agarotetraose as the major product. Optimum pH is 8.5. Active between pH 4.5 and 9.5, stable between pH 6.5 and 10.5. Optimum temperature is 45 degrees Celsius. Stable up to 40 degrees Celsius. Monomer. Belongs to the glycosyl hydrolase 96 family.