A theoretical investigation is performed of the complexes of a tetracationic porphyrin, tetra-(4-N-methylpyridyl)-porphyrin, (T4MPyP), with the hexanucleotides d(CGCGCG)2 and d(TATATA)2, considering the possibility of both the intercalative and the groove binding interactions. These computations demonstrate that T4MPyP manifests a significant preference for intercalation in its complex with d(C...

Let IF be field, and let A and B be n X n matrices with elements in IF. Suppose that A is completely reducible and that B is symmetric. If the principal minors of A determined by the 1and 2-circuits of the graph of B and by the chordless circuits of the graph of A are equal to the corresponding principal minors of B, then A is diagonally similar to B; and conversely.

Path-addition is an operation that takes a graph and adds an internally vertex-disjoint path between two vertices together with a set of supplementary edges. Path-additions are just the opposite of taking minors. We show that some classes of graphs are closed under path-addition, including non-planar, right angle crossing, fan-crossing free, quasi-planar, (aligned) bar 1-visibility, and interva...

WOPR-domain proteins are found throughout the fungal kingdom where they function as master regulators of cell morphology and pathogenesis. Genetic and biochemical experiments previously demonstrated that these proteins bind to specific DNA sequences and thereby regulate transcription. However, their primary sequence showed no relationship to any known DNA-binding domain, and the basis for their...

We present here for the first time the crystal structure of an AT-hook domain. We show the structure of an AT-hook of the ubiquitous nuclear protein HMGA1, combined with the oligonucleotide d(CGAATTAATTCG)(2), which has two potential AATT interacting groups. Interaction with only one of them is found. The structure presents analogies and significant differences with previous NMR studies: the AT...

We show that a graph of girth greater than 6 log k + 3 and minimum degree at least 3 has a minor of minimum degree greater than k. This is best possible up to a factor of at most 9/4. As a corollary, every graph of girth at least 6 log r + 3 log log r + c and minimum degree at least 3 has a Kr minor.

The sequence of frond emergence and the intervals required for daughter colony separation have been determined for Lemna paucicostata Hegelm. 6746 growing under standardized conditions. After separation of a new mother colony, the first daughter colony is produced from the left meristematic pocket and separates after approximately 60 hours, the second daughter, produced from the right pocket, s...

The Gram dimension gd(G) of a graph is the smallest integer k ≥ 1 such that, for every assignment of unit vectors to the nodes of the graph, there exists another assignment of unit vectors lying in R, having the same inner products on the edges of the graph. The class of graphs satisfying gd(G) ≤ k is minor closed for fixed k, so it can characterized by a finite list of forbidden minors. For k ...