We study a simple heteropolymer model containing sequence-independent local interactions on both square and triangular lattices. Sticking to a two-letter code, we investigate the model for varying strength of the local interactions; = 0 corresponds to the well-known HP model K.F. Lau and K.A. Dill, Macromolecules 22, 3986 (1989)]. By exhaustive enumerations for short chains, we obtain all struc...

We consider a two-letter self-avoiding lattice heteropolymer model of NH (out of N) attracting sites. At zero temperature, chain size scales as N1/dF (ρH = NH/N) with novel universal exponents describing asymptopia (d is space dimension). The phase diagram includes a new multicritical point at ρH < 1 where a line of collapse critical points ends at a freezing transition, with entropy approachin...

Lycophytes arose in the early Silurian ( approximately 400 Mya) and represent a major lineage of vascular plants that has evolved in parallel with the ferns, gymnosperms, and angiosperms. A hallmark of vascular plants is the presence of the phenolic lignin heteropolymer in xylem and other sclerified cell types. Although syringyl lignin is often considered to be restricted in angiosperms, it has...

The configuration space network (CSN) of a dynamical system is an effective approach to represent the ensemble of configurations sampled during a simulation and their dynamic connectivity. To elucidate the connection between the CSN topology and the underlying free-energy landscape governing the system dynamics and thermodynamics, an analytical solution is provided to explain the heavy tail of ...

We have performed multicanonical simulations of hydrophobic-hydrophilic heteropolymers with two simple effective, coarse-grained off-lattice models to study the influence of specific interactions in the models on conformational transitions of selected sequences with 20 monomers. Another aspect of the investigation was the comparison with the purely hydrophobic homopolymer and the study of gener...

We consider the design of proteins to be simultaneously thermodynamically stable in multiple independent and correlated conformations. We first show that a protein can be trained to fold to multiple independent conformations and calculate its capacity. The number of configurations that it can remember is proportional to the logarithm of the number of amino acid species A, independent of chain l...

Collagen is the most abundant protein of animal origin, comprising approximately 30% of total animal protein. There are at least 19 variants of collagen, named type I to XIX. Types I, II, III and V are the fibrous collagens. Type I collagen is found in all connective tissue, including bones and skins. It is a heteropolymer of two "1 chains and one "2 chain. It consists of one-third glycine, con...

There have been mainly three approaches to study the protein folding (PF) problem: One is the experimental determination of the PF. In this approach, submillisecond laser pulse spectroscopy experiments have revealed the nature of the relaxation process from unfolded to folded structures in the PF. The second is the so-called inverse PF problem. In this approach, it has been conjectured that the...

Chitosan is a linear heteropolymer consisting of β 1,4-linked N-acetyl-D-glucosamine (GlcNAc) and D-glucosamine (GlcN). We have compared the antifungal activity of chitosan with DPn (average degree of polymerization) 206 and FA (fraction of acetylation) 0.15 and of enzymatically produced chito-oligosaccharides (CHOS) of different DPn alone and in combination with commercially available syntheti...