Showing papers by "Federico Morán published in 1988"
TL;DR: The behavior of a two-variable biochemical model in conditions where it admits multiple oscillatory domains in parameter space is analyzed, providing a qualitative explanation for experimental observations related to the occurrence of two different modes of oscillations in thalamic neurones.
Abstract: We analyze the behavior of a two-variable biochemical model in conditions where it admits multiple oscillatory domains in parameter space. The model represents an autocatalytic enzyme reaction with input of substrate both from a constant source and from non-linear recycling of product into substrate. This system was previously studied for birhythmicity, i.e. the coexistence between two stable periodic regimes (Moran and Goldbeter 1984), and for multi-threshold excitability (Moran and Goldbeter 1985). When two distinct oscillatory domains obtain as a function of the substrate injection rate, the system is capable of exhibiting two markedly different modes of oscillations for slightly different values of this control parameter. Phase plane analysis shows how the multiplicity of oscillatory domains depends on the parameters that govern the underlying biochemical mechanism of product recycling. We analyze the response of the model to various kinds of transient perturbations and to periodic changes in the substrate input that bring the system through the two ranges of oscillatory behavior. The results provide a qualitative explanation for experimental observations (Jahnsen and Llinas 1984b) related to the occurrence of two different modes of oscillations in thalamic neurones.
30 citations
TL;DR: An empirical method for finding complex oscillatory phenomena in autonomous biochemical systems, not subjected to forcing by a periodic input is outlined, which relies on finding in parameter space two domains of instability of the steady state and bringing them close to each other until they merge.
16 citations
TL;DR: A BASIC program (CDPROT) has been developed to calculate the secondary structure of proteins from their far UV circular dichroism spectrum, representing on screen both theoretical and experimental spectra indicating the root-mean-square error.
Abstract: A BASIC program (CDPROT) has been developed to calculate the secondary structure of proteins from their far UV circular dichroism spectrum. This implementation can use different reference spectra, calculated either from model polypeptides or proteins of known tertiary structure. Apart from obtaining the alpha-helical, beta-structure, beta-turns or random percentages which would generate the spectrum of best fit with respect to the experimental measures, CDPROT represents on screen both theoretical and experimental spectra indicating the root-mean-square error. The provision of additional reference spectra by the user is also considered, and another program (STOREREF) performs the editing in an adequate format for CDPROT.
12 citations