Properties of mnemiopsin and berovin, calcium-activated photoproteins from the ctenophores Mnemiopsis sp. and Beroe ovata

Journal Article · Tue Jan 01 04:00:00 EST 1974 · Biochemistry; (United States)

OSTI ID:6543448

Ward, W W; Seliger, H H

By methods previously described, the calcium-activated bioluminescent photoproteins were extracted with EDTA from the ctenophores Mnemiopsis sp. and Beroue ovata and then purified extensively. Two forms of the Mnemiopsis photoprotein, mnemiopsin-1 and mnemiopsin-2, and the single Beroue photoprotein, berovin, have been characterized and compared with respect to their physical and spectral properties. Ctenophore photoproteins react in vitro with calcium ions in molar excess of EDTA to produce a rapid flash with first-order decay kinetics. The rates and total light yields of these reactions are differently dependent on pH, temperature, and ionic strength. Mnemiopsin activation is specific for calcium ions. However, under certain assay conditions and at low metal ion concentrations a large number of cations appear to activate mnemiopsin. But at higher concentrations, most of these cations are inhibitors. Among these, only Mg/sup 2 +/ and Ba/sup 2 +/ are completely reversible competitive inhibitors of bioluminescence. Total photon yields are enhanced by preincubation with certain hydrophilic alcohols but reduced with long-chain aliphatic alcohols. Molecular weights were estimated by gel filtration on Sephadex and Bio-Gel and by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The most reliable molecular weight estimates were 24,000, 27,500, and 25,000 awu for m-1, m-2, and berovin, respectively. Physical and spectral similarities among these photoproteins and the bioluminescent systems of the jellyfish Aequorea and the sea pansy Renilla suggest that similar biochemical mechanisms may exist among all of the bioluminescent coelenterates.

• Research Organization: Johns Hopkins Univ., Baltimore
• OSTI ID: 6543448
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 13:7; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METALS
AMINO ACIDS
ANIMALS
BIOASSAY
BIOCHEMICAL REACTION KINETICS
CALCIUM
CARBOXYLIC ACIDS
CATIONS
CHARGED PARTICLES
CHELATING AGENTS
CNIDARIA
COMPARATIVE EVALUATIONS
EDTA
ELEMENTS
EMISSION
EMISSION SPECTRA
INVERTEBRATES
IONS
KINETICS
LUMINESCENCE
METALS
MOLECULAR WEIGHT
OPTICAL PROPERTIES
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOTOLUMINESCENCE
PHOTON EMISSION
PHYSICAL PROPERTIES
PROTEINS
REACTION KINETICS
SPECTRA