Effect of N- and C-terminal functional groups on the stability of collagen triple helices.

The effect of charged versus neutral N- and C-termini on the stability of the collagen triple helix was examined. Thermal denaturation studies at different pH with collagen model peptides showed that an ammonium group at the N-terminus destabilizes the triple helix more than a carboxylate at the C-terminus. A neutral carboxylic acid stabilizes the triple helix more than an amido moiety at the C-terminus.

Comparison of boron-assisted oxime and hydrazone formations leads to the discovery of a fluorogenic variant.

We use kinetic data, photophysical properties, and mechanistic analyses to compare recently developed high-rate constant oxime and hydrazone formations. We show that when Schiff base formation between aldehydes and arylhydrazines is carried out with an appropriately positioned boron atom, then aromatic B-N heterocycles form irreversibly. These consist of an extended aromatic structure amenable to the tailoring of specific properties such as reaction rate and fluorescence. The reactions work best in neutral aqueous buffer and can be designed to be fluorogenic - properties which are particularly interesting in bioconjugation.