Synthesis and mobilization of glycogen during metamorphosis of the medfly Ceratitis capitata.

There are no recent reports focusing on insect glycogen metabolism that take the advances made in mammalian and yeast systems into account. Moreover, little is known about glycogen synthesis and degradation during insect metamorphosis. The biosynthesis and mobilization of insect glycogen were measured during the larva to adult transition in the Medfly, Ceratitis capitata.

Glycogen brain branching enzyme.

Rat brain glycogen branching enzyme was partially purified in order to elucidate its mechanism of action. The alpha1,4-alpha1,6-glucan polysaccharide was synthesized using rat brain branching enzyme under two different elongation conditions: Glc-1-P and phosphorylase or UDP-Glc and glycogen synthase. The products obtained demonstrated that the cpolysaccharides synthesized (pattern of the spectra obtained in the presence of Krisman's reagent, lambda max, parameter A and R, % beta-amylolysis and degree of branching) under different incubation times are nearly constant.

Progress in the understanding of glycogen biogenesis in rat heart.

The sequence of glucosylation steps from "genesine", the naked initiation protein, to rat heart glycogen are described. During a pulse experiment with UDP-14C-glucose the radiolabelled 14C-glucosylated protein band of 38 and 42 kDa appeared first. Mn+2 stimulates the first transfer of glucoses to "genesine" and the 38 kDa and 42 kDa protein bands appear.

Further studies on the "de novo" process of alpha 1,4-alpha 1,6 glucopolysaccharides--corn starch biogenesis.

Starch biogenesis in corn endosperm from Flint, Sugary, Waxy, as a function of the grain filling/period was studied. We have differentially identified the initiation from the elongation process. After incubating under unprimed conditions, two glucose radiolabelled protein bands of 39,5 and 36 kDa were obtained.

Further studies on the primer formation for glycogen biosynthesis in rat heart.

Using selected incubation conditions we have identified intermediate steps, between the first glucose transferred to protein and the appropriate substrate for glycogen synthase. Mn2+ stimulates the addition of the first, and probably, the second glucose molecule to the acceptor protein but inhibits further elongation. In the presence of Mn2+ only one radioglucosylated protein band of M(r) 42 kDa was evident.