The properties of hemoglobin denaturation caused by two anionic surfactants (sodium dodecylsulfate and sodium lauroylmethyltaurate) were examined using spectrophotometry (multi-plate reader), circular dichroism (CD) and high-performance liquid chromatography (HPLC), and their denaturating action on hemoglobin and sorption to it were examined by various methods. Correlation and factorial analyses were applied to the experimental data and the following results were obtained: (1) High correlations were found among sorption, denaturation and alpha-helix content and the random structure of hemoglobin. (2) The alpha-helix of hemoglobin is randomized as the surfactants denature hemoglobin. (3) Factorial analysis indicates that there are two factors involved in hemoglobin denaturation, one related to the destruction of the alpha-helix and the other related to a change in the beta-structure. These two factors are related to change in the environment around the heme group. (4) Destruction of the alpha-helix seems to be one of the causes of the eye irritation produced by anionic surfactants.
ABSTRACT-Mobilization of Ca++ was estimated in single rabbit blood platelets with digital imaging microscopy. Concanavalin A (Con A) caused a rapid initial in crease in intracellular concentration of Ca++ ([Ca++];) with a latent time of about 20 sec, followed by a sustained increase in [Ca++];. This effect of Con A was antago nized by a-methyl-D-mannose, which already was shown to antagonize the inhibitory effect of Con A on 5-HT transport, indicating that this effect of Con A was also de rived from its binding to cell surface glycoproteins. The presence of EGTA in the medium did not affect the initial rise, but inhibited the latter phase of sustained rise. Thus, Con A induced elevation of [Ca++]; was suggested to consist of two different processes: mobilization of Ca+ + from the intracellular storage sites and successive Ca + + influx through Ca + + channels. The effect of Con A on the 5-HT transport was tested in the presence of EGTA, a condition where no Ca+ + influx occurs. The re sults indicate that Con A induced inhibition of 5-HT transport was not influenced by EGTA in the medium. It is suggested that the effect of Con A on 5-HT transport might be exerted through the Ca ++ mobilization from its intracellular storage sites.
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