Experimental evidence for condensation reactions between sugars and proteins in carbonate skeletons

Journal Article · Wed Apr 01 00:00:00 EST 1992 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(92)90223-6· OSTI ID:5371497

Collins, M J; Westbroek, P; Muyzer, G ^[1]; De Leeuw, J W ^[2]

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1. Leiden Univ. (Netherlands)
2. Delft Univ. of Technology (Netherlands)

Melanoidins, condensation products formed from protein and polysaccharide precursors, were once thought to be an important geological sink for organic carbon. The active microbial recycling of the precursors, coupled with an inability to demonstrate the formation of covalent linkages between amino acids and sugars in melanoidins, has shaped a powerful argument against this view. Yet, melanoidins may still be an abundant source of macromolecules in fossil biominerals such as shells, in which the proteins and polysaccharides are well protected from microbial degradation. The authors have modeled diagenetic changes in a biomineral by heating at 90C mixtures of protein, polysaccharides, and finely ground calcite crystals in sealed glass vials. Changes to the protein bovine serum albumin (BSA, fraction V) were monitored by means of gel electrophoresis and immunology. In the presence of water, BSA was rapidly hydrolyzed and remained immunologically reactive for less than 9 h. Under anhydrous conditions the protein was immunologically reactive for the whole period of the experiment (1,281 h), unless mono- or disaccharide sugars were also present. In the presence of these reactive sugars, browning, a discrete increase in molecular weight of the protein, and a concomitant loss of antigenicity confirmed that the sugars were attaching covalently to the protein, forming melanoidins. The authors roughly estimate that, at the global scale, 2.4 {times} 10{sup 6} tons of calcified tissue matrix glycoproteins is processed annually through the melanoidin pathway. This amount would be equivalent to 7 per mil of the total flux of organic carbon into marine sediments.

• OSTI ID: 5371497
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 56:4; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
AMINO ACIDS
DEHYDROCYCLIZATION
CARBONATE ROCKS
DIAGENESIS
SACCHARIDES
CALCITE
CARBON COMPOUNDS
CARBON CYCLE
CARBON SINKS
CHEMICAL REACTION KINETICS
ELECTROPHORESIS
FOSSILS
HYDROLYSIS
INVERTEBRATES
MINERAL CYCLING
PROTEINS
SKELETON
ANIMALS
BODY
CARBOHYDRATES
CARBONATE MINERALS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECOMPOSITION
KINETICS
LYSIS
MINERALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
REACTION KINETICS
ROCKS
SEDIMENTARY ROCKS
SINKS
SOLVOLYSIS
580000* - Geosciences