Discrete dissolved and particulate proteins in oceanic waters

Abstract

Dissolved and particulate proteins were extracted from samples of surface seawater collected from the equatorial area, through the Indian Ocean, to the Antarctic Ocean. Dissolved proteins were also observed in waters of the equatorial Pacific. Dissolved and particulate proteins with a wide range of molecular masses were detected by sodium dodecylsulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). The particulate proteins were made up of many background proteins of overlapping molecular weight, which caused uniform staining in the gel. However, distinct bands of individual proteins with apparent molecular masses of ∼66 and 45 kDa were evident among the background proteins. Electrophoretograms of dissolved proteins were quite different from those of the particulate proteins. The dissolved background proteins were not significant, and fewer than 30 proteins were clearly visualized as major dissolved proteins. Dissolved proteins with apparent molecular masses of 48 and 37 kDa were commonly found as major proteins in all samples examined. Such molecular characteristics of dissolved and particulate proteins are consistent with previous results from the North Pacific. Thus, it appears that the processes by which specific proteins from marine organisms are transferred to and accumulated in the pools of dissolved and particulate organic matter are identical throughout the world’s oceans.

Degradation by bacteria of membrane and soluble protein in seawater

“…These results probably explain in part selective accumulation of porin molecules in oceanic waters (Tanoue et al 1995(Tanoue et al , 1996. More generally, membrane and soluble proteins should be degraded differently regardless of the source of the protein, w h~c h implies that our results should apply to dissolved proteins released by phytoplankton and heterotrophic protists along with sloppy feeding, viral infection and other mortality processes.…”

“…An alternative, if not mutually exclusive, hypothesis is that selected components of cellular material do not need modification in order to resist microbial degradation and thus are selectively preserved in seawater while other material is degraded. Recent research has suggested that dissolved proteins in oceanic waters are dominated by only a limited number (<30) of protein molecules, one of which was identified to be a bacterial outer membrane protein, porin (Tanoue et al 1995(Tanoue et al , 1996. However, the mechanism by which porins and other membrane proteins are selectively preserved in seawater is not clear.…”

Relations between bacterial nitrogen metabolism and growth efficiency in an estuarine and an open-water ecosystem

“…Similar production of amino acids from DCAA previously taken up would not have necessarily been registered in our experiments, as uptake or release of DCAA was determined from changes in concentration. Commonly found proteins in seawater are 37 and 48 kDa molecules, of which the latter has homologies to the rather proteaseresistant bacterial membrane protein porin (Tanoue et al 1996). Thus, constituents of bacterial cells probably make up a portion of the DCAA pool.…”

Coexisting protist-bacterial community accelerates protein transformation in microcosm experiments

“…It is generally assumed that proteins are labile in seawater and thus are not readily preserved (Hollibaugh and Azam, 1983). However, research has indicated that proteinaceous materials are preserved in freshwater, estuarine, and marine waters and sediments (Tanoue, 1995;Tanoue et al, 1996;Harvey, 1997, 1998;Fogel and Tuross, 1999;Pantoja and Lee, 1999a;Moore et al, 2012). Tanoue et al (1995), found that approximately 30 polypeptides with molecular masses ranging from 30 to 48 kDa were detected in seawater samples collected from the Arctic to the Antarctic.…”