Photoreconversion of blowfly visual pigment proceeds through a slowly (13 ms) decaying intermediate

Summary The photochemical cycle of the visual pigment molecules in the blowflyCalliphora erythrocephala was investigated by transmission measurements, making use of the fact that intermediate states of the visual pigment molecules each have a characteristic absorption spectrum.It is shown that the conversion of metaxanthopsin (M 580) to the native xanthopsin state (P 490) induced by an orange-red light pulse proceeds through a newly discovered intermediate (N), which thermally decays with a time constant of about 13 ms at room temperature.The absorption spectrum of N peaks in the blue-green at about 490 nm. In the green and orange N absorbs more strongly than the native xanthopsin, but in the blue N and xanthopsin absorb almost equally. The latter finding explains why N has remained undetected in earlier studies.Abbreviations ERP early receptor potential - M metaxanthopsin - P xanthopsin     

The formation of L-3-phosphoglyceric acid by ribulose-1,5-bisphosphate carboxylase

A sensitive and reliable method to determine the stereochemical composition of 3-phosphoglyceric acid is presented. Results obtained with this method show that 3-phosphoglyceric acid formed in the ribulose-1,5-bisphosphate carboxylase reaction is a mixture of 10% L-3-PGA and 90% D-3-PGA.     

Effect of feeding pattern on the sensitivity of hepatic carnitine palmitoyl-transferase to inhibition by malonyl-CoA in the rat

1. The feeding pattern influences the inhibitory effects of malonyl-CoA on carnitine palmitoyltransferase-I. 2. The sensitivity of liver carnitine palmitoyltransferase-I to malonyl-CoA is increased in rats meal-fed when compared to rats fed ad libitum. 3. Moreover, liver carnitine palmitoyltransferase-I of meal-fed rats remains more sensitive to inhibition by malonyl-CoA during a 24 hour fast than liver carnitine palmitoyltransferase-I of rats previously fed ad libitum.     

Resistance to the peptide-like antibiotic negamycin in Escherichia coli

An $\text{Escherichia coli}$ mutant resistant to the peptide-like antibiotic negamycin carries a mutation, NEG40, which maps at minute 65 on the bacterial genome. Termination of protein synthesis, which is normally blocked by negamycin in wild type cellular extracts, continues with cellular extracts from the mutant in the presence of the drug; indeed, release of complete peptides from the polysomes still proceeds over a wide range of drug concentrations. The data suggest that the NEG40 mutation affects one of the components of the termination complex (ribosome or release factor).