Flow calorimetry of the sorption of butanols to elastin preparations and comparison with surface areas determined by krypton-85 adsorption.
1. The apparent surface areas of elastin samples as well as of several other fibrous protein preparations (collagen, keratin, polymeric stroma of aorta) were determined using two different approaches: (a) the Brunauer-Emmett-Teller method with 85Kr and (b) microflow calorimetry with n- and tert.-butanol as adsorbents in a heptane stream. 2. Areas of heat signals obtained by flow calorimetry for the adsorption and desorption of n- and tert.-butanol were substantially equivalent; desorption was more protracted than adsorption, the difference between the speed of desorption and adsorption increased with decreasing chain length of the alcohols (methanol, ethanol, n-propanol and n-butanol). 3. An inverse linear relationship was found between the energy change recorded during the adsorption process and the chain length of the alcohols (methanol, ethanol, n-propanol, n-butanol). 4. Heats of adsorption of tert.-butanol were systematically found to be significantly lower than those of n-butanol with all the protein samples investigated. 5. The apparent surface areas of the protein samples determined with tert.-butanol were on the average of the same order or only slightly higher than those obtained with 85Kr. Results obtained with n-butanol were significantly higher. The difference between surface areas obtained with n- and tert.-butanol depended on the nature of the protein sample, on its method of preparation and to some extent on the residual humidity of the sample. 6. The results could be explained on the basis of the hydrophobic theory of elastin structure (see ref. 4) and confirmed our former conclusions (see ref. 3) concerning the significantly higher surface areas of elastin samples purified by different procedures as compared to collagen or to keratin. They also confirmed the accessibility of the surface of elastic fibers to the molecular probes used in the polymeric stroma of aorta.
Robert
L
L
Laboratoire de Biochimie du Tissu Conjonctif (Equipe de Recherche du CNRS), Paris, France.
Robert
B
B
Houtman
J P
JP
Stack
M V
MV
D000327:Adsorption; D000818:Animals; D001665:Binding Sites; D000440:Butanols / Q000737:chemistry*; D002151:Calorimetry / Q000379:methods; D002417:Cattle; D004549:Elastin / Q000737:chemistry*; D005561:Formates / Q000737:chemistry; D006536:Heptanes / Q000737:chemistry; D006801:Humans; D007727:Krypton Radioisotopes / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
D000440:Butanols; D005561:Formates; D006536:Heptanes; D007727:Krypton Radioisotopes; C030544:formic acid; D004549:Elastin