Purification and partial characterization of a type V like collagen from the muscle of marine prawn,Penaeus indicus

Habitual Dietary Collagen Intake Is Lower in Females and Older Irish Adults Compared with Younger Males

BACKGROUND

Collagen ingestion reportedly benefits connective tissues, such as skin, bone, muscle, tendon, and ligament. However, the quantity of collagen intake in the diet of European adults is unknown.

OBJECTIVES

This study aims to investigate collagen intake in the habitual diets of Irish adults, and whether it differed according to sex and/or age.

METHODS

We conducted secondary analysis of the Irish National Adult Nutrition Survey, which assessed typical dietary intake using a 4-d food diary in 1500 adults, aged 18-90 y. We categorized participants into 3 age groups: young (18-39 y, n = 630), middle-aged (40-64 y, n = 644), and older (≥65 y, n = 226) adults. Collagen composition of each individual food item in the database was determined by applying a percentage collagen value from analytical sources, allowing computation of collagen mean daily intake (MDI), collagen MDI relative to body mass, and collagen/total protein MDI. Differences in intakes between age groups and sexes were evaluated using physical activity level as a covariate.

RESULTS

Collagen MDI for the entire population was 3.2 ± 2.0 g/d, representing 3.6% ± 1.9% total protein intake. Males had higher absolute and relative collagen MDI than females, regardless of age (4.0 ± 2.1 g/d compared with 2.3 ± 1.4 g/d, P < 0.001), whereas older adults had lower absolute collagen MDI than middle-aged adults (2.9 ± 1.8 g/d compared with 3.3 ± 2.0 g/d, P = 0.021).

CONCLUSIONS

Collagen intake in the Irish adult population was considered low (relative to total protein intake and to dose-response studies), particularly in females and older individuals. Increasing daily collagen intake may therefore be warranted to optimize the health of collagen-rich tissues.

Diverse and Productive Source of Biopolymer Inspiration: Marine Collagens

Marine biodiversity is expressed through the huge variety of vertebrate and invertebrate species inhabiting intertidal to deep-sea environments. The extraordinary variety of "forms and functions" exhibited by marine animals suggests they are a promising source of bioactive molecules and provides potential inspiration for different biomimetic approaches. This diversity is familiar to biologists and has led to intensive investigation of metabolites, polysaccharides, and other compounds. However, marine collagens are less well-known. This review will provide detailed insight into the diversity of collagens present in marine species in terms of their genetics, structure, properties, and physiology. In the last part of the review the focus will be on the most common marine collagen sources and on the latest advances in the development of innovative materials exploiting, or inspired by, marine collagens.

Characterisation of proteolytic enzymes from muscle and hepatopancreas of fresh water prawn (Macrobrachium rosenbergii)

BACKGROUND

Fresh water prawn in Thailand is widely consumed due to its delicacy. During postmortem handling and storage, prawn meat becomes soft and mushy, probably as a result of indigenous proteases. Therefore, an understanding of prawn proteases associated with the degradation of muscle proteins from fresh water prawn could pave the way for prevention of such a phenomenon during extended storage.

RESULTS

Proteolytic enzymes in the crude extract (CE) from muscle and hepatopancreas of fresh water prawn (Macrobrachium rosenbergii) were characterised. CE from muscle exhibited the highest hydrolytic activities towards haemoglobin at pH 5 and 50 °C, while that from hepatopancreas had the highest activity on casein at pH 7 and 60 °C. Based on inhibitor study, cysteine protease and serine protease were dominant in CE from muscle and hepatopancreas, respectively. CE from muscle rarely hydrolysed natural actomyosin (NAM), but could not degrade pepsin-soluble collagen (PSC). Conversely, NAM and PSC were susceptible to hydrolysis by CE from hepatopancreas as evidenced by the marked decreases in band intensity. Activity staining using haemoglobin, casein and gelatin as substrates revealed that no proteolytic or gelatinolytic activity was observed in CE from prawn muscle, while CE from hepatopancreas exhibited pronounced hydrolytic activities towards all substrates. CE from muscle showed calpain and cathepsin L activities but CE from hepatopancreas mainly exhibited tryptic and chymotryptic activities.

CONCLUSION

Serine proteases, mainly trypsin-like or chymotrypsin-like, from hepatopancreas were probably responsible for the softening of prawn meat during postmortem storage via the degradation of both muscle and connective tissues.

Molecular species of collagen in the intramuscular connective tissues of the marine crab, Scylla serrata

Type V like collagens are widely distributed in marine invertebrates, particularly crustaceans and molluscs. We have been investigating the nature of collagens in the muscular tissues of crustaceans. The presence of type V like homotrimeric collagen in prawn muscle was noted before. We report here a comparative analysis of collagens purified from the pepsin digest of abdominal and pereiopod muscle tissues of the crab, Scylla serrata. The major collagen in either muscle precipitated at 1.2 M NaCl at acid pH, suggestive of a type V like property. The homotrimeric collagen was then purified to near homogeneity by precipitation with 20% ammonium sulphate. Solubility characteristics and biochemical studies indicated the leg muscle collagens to be highly crosslinked and stabilised by more bound carbohydrates, as compared to the abdominal muscle collagen. Analysis of amino acid composition revealed a close similarity to known type V collagens and the leg muscle collagen was characterised by more lysine hydroxylation and slightly reduced glycine content. The leg muscle collagen had a higher denaturation temperature and intrinsic viscosity than the abdominal muscle collagen. Our results confirm the similarity of major crustacean muscle collagens to vertebrate type V collagen. Further, the relative complexity of leg muscle collagen, unlike the abdominal muscle collagen, correlates to the specific functional requirements, where the former is involved in locomotion and preying and the latter in normal growth and development.

Occurrence of a novel collagen with three distinct chains in the cranial cartilage of the squid Sepia officinalis: comparison with shark cartilage collagen

A unique collagen with three distinct chains, was purified from the cranial cartilage of the squid Sepia officinalis, by pepsinisation and salt precipitation and compared with shark cartilage collagen. These chains, which were different from the known cartilage collagen chains, were referred as C1, C2 and C3, had approximate molecular weights of 105 kDa, 115 kDa and 130 kDa, respectively, and were present in a ratio of 3:2:1, suggestive of two molecules of composition, [(C1)2C2] and [C1C2C3]. These collagens were purified by fractionation at acid and neutral pH, and by ammonium sulfate precipitation. Solubility data indicated that this collagen was more crosslinked than the type I collagen isolated from cartilage of shark, Carcharius acutus. In vitro fibrillogenesis revealed that the sepia collagen formed denser aggregates, as compared to shark collagen, and was stabilised by a higher degree of carbohydrate association. Polyclonal antisera raised against shark collagen was also reactive against the sepia collagens, while the converse was not true, indicating the high immunospecificity of the latter. These results demonstrate collagen polymorphism in an invertebrate cartilage and may hold significance in understanding tissue calcification and molecular evolution. Further, these collagens may represent ancestral forms of vertebrate minor collagens like typeV/XI.