Preparation of hoki (Johnius belengerii) bone oligophosphopeptide with a high affinity to calcium by carnivorous intestine crude proteinase

In the present study, the skeletons discarded from industrial processing of hoki (Johnius belengerii) were digested by a heterogeneous enzyme extracted from the intestine of a carnivorous fish (also discarded from industrial processing), bluefin tuna (Thunnus thynnus), in order to utilize the bone in nutraceuticals with a high bioavailability of calcium. The tuna intestine crude enzyme (TICE) could effectively biodegrade the hoki bone matrices composed of collagen, non-collageneous proteins, carbohydrates and minerals. A fish bone phosphopeptide (FBP) containing 23.6% of phoshorus was isolated from the hoki bone hydrolysates degraded by TICE using HA affinity chromatography and gel permeation chromatography. After the FBP, with a molecular mass of 3.5 kDa, was interacted with calcium, 41.1 mg/l of soluble calcium were maintained at 20 mM phosphate buffer (pH 7.8) without the formation of insoluble calcium phosphate. The results provide evidence that the carnivorous fish intestine enzyme (TICE) could degrade the teleost (J. belengerii) bone, and the fish bone oligophosphopeptide prepared by the enzymatic degradation of the bone could be utilized as a nutraceutical with a potential calcium-binding activity.