Amino acid sequences can be described as foldable or un-foldable depending on the nature of the tertiary structures they produce. Thus, understanding what makes a sequence foldable or un-foldable is crucial not only for classifying the huge number of sequences being produced by the various genome projects but also for understanding how amino acid sequence determines tertiary structure, that is, solving the protein folding problem. Through systematic circular permutation analysis of a small globular protein, dihydrofolate reductase, an idea of folding element has been introduced and led us to the conclusion that a complete set of folding elements, which leads to a collapse of the molecule in the early stages of folding, is required for a protein to be foldable.
The presence of multiple types of cone visual pigments with different absorption maxima is one of the molecular bases of colour vision. Because all of the visual pigments investigated so far contain 11-cis-retinal or its derivatives, the spectral shift would reflect the specific interaction of 11-cis-retinal with nearby amino acid residues. In addition, there is a unique mechanism of spectral red-shift observed in the visual pigments that have a chloride binding site. Here, we summarize recent investigations on the mechanism of spectral tuning in visual pigments including those having a chloride-binding site.
Brain is an emotional computer which has as effective capacity of learning and memory about things which move/impress us. Stress suppresses but deep impression enhances capacity of learning and memory. Neuronal mechanisms of learning and memory are significantly dependent on our mind and emotion, as judged form our experiences. We are trying to resolve molecular basis of these neuronal processes by means of function of neurosteroids (brain steroids).