RESUMEN
Isotope effects of four broad and overlapping categories have been applied to the study of the mechanisms of chemical reaction and regulation of nonheme diiron cluster-containing oxygenases. The categories are: (a) mass properties that allow substrate-to-product conversions to be tracked, (b) atomic properties that allow specialized spectroscopies, (c) mass properties that impact primarily vibrational spectroscopies, and (d) bond dissociation energy shifts that permit dynamic isotope effect studies of many types. The application of these categories of isotope effects is illustrated using the soluble methane monooxygenase system and CmlI, which catalyzes the multistep arylamine to arylnitro conversion in the biosynthetic pathway for chloramphenicol.
Asunto(s)
Espectroscopía de Resonancia por Spin del Electrón/métodos , Isótopos/química , Oxigenasas/química , Espectroscopía de Mossbauer/métodos , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Vías Biosintéticas , Cloranfenicol/biosíntesis , Cloranfenicol/química , Espectroscopía de Resonancia por Spin del Electrón/instrumentación , Compuestos Férricos/química , Cinética , Modelos Moleculares , Oxidación-Reducción , Oxigenasas/metabolismo , Espectroscopía de Mossbauer/instrumentación , Streptomyces/metabolismoAsunto(s)
Biología Computacional/métodos , Proteínas Hierro-Azufre/química , Animales , Bacterias/química , Bacterias/metabolismo , Espectroscopía de Resonancia por Spin del Electrón/instrumentación , Humanos , Proteínas Hierro-Azufre/metabolismo , Proteínas Hierro-Azufre/ultraestructura , Espectrometría de Masas/instrumentación , Espectroscopía de Mossbauer/instrumentaciónRESUMEN
A new method of performing Mössbauer spectroscopy with synchrotron radiation is demonstrated that involves using a high-speed periodic shutter near the focal spot of a microfocused X-ray beam. This fast microshuttering technique operates without a high-resolution monochromator and has the potential to produce much higher signal rates. It also offers orders of magnitude more suppression of unwanted electronic charge scattering. Measurement results are shown that prove the principle of the method and improvements are discussed to deliver a very pure beam of Mössbauer photons (E/ΔE ≃ 10(12)) with previously unavailable spectral brightness. Such a source will allow both Mössbauer spectroscopy in the energy domain with the many advantageous characteristics of synchrotron radiation and new opportunities for measurements using X-rays with ultra-high energy resolution.
