Abstract: There is provided a process for preparing a compound represented by the following general formula (1) or a salt thereof, which comprises exchanging one or more of an amino proton in a compound represented by the following general formula (2) or a salt thereof to deuterium, and after the exchanging, converting a deuterium-exchanged compound of the compound represented by the general formula (2) or a salt thereof into the compound represented by the general formula (1) or a salt thereof: wherein, in the general formula (1), one, or two or more of hydrogen atom may be substituted with their isotope; and in the general formula (2), each of R1 is independently hydrogen atom, tert-butyloxycarbonyl group or benzyloxycarbonyl group, and R2 is independently tert-butyl group, benzyl group, methyl group or ethyl group.

Abstract: There is provided a process for preparing a compound represented by the following general formula (1) or a salt thereof, which comprises exchanging one or more of an amino proton in a compound represented by the following general formula (2) or a salt thereof to deuterium, and after the exchanging, converting a deuterium-exchanged compound of the compound represented by the general formula (2) or a salt thereof into the compound represented by the general formula (1) or a salt thereof: wherein, in the general formula (1), one, or two or more of hydrogen atom may be substituted with their isotope; and in the general formula (2), each of R1 is independently hydrogen atom, tert-butyloxycarbonyl group or benzyloxycarbonyl group, and R2 is independently tert-butyl group, benzyl group, methyl group or ethyl group.

Abstract: A process for preparing a compound represented by the following general formula (I) or a salt thereof, which comprises reacting lysine or a protective product thereof or a salt thereof with allysine or a protective product thereof in the presence of a specific trifluoromethane sulfonate to obtain a compound having pyridine ring or a salt thereof. (wherein, in the above-described general formula (I), one of R1 and R2 is —CH2CH2CH2CH(NH2)COOH group, and the other is hydrogen atom. And wherein, in the above-described general formula (I), one, or two or more of hydrogen atom, one, or two or more of carbon atom, or one, or two or more of nitrogen atom may be substituted with their isotope.

Abstract: The present invention provides, inter alia, methods for measuring the amount of a marker of elastic fiber injury in a sample. The methods include contacting a sample with a compound of formula (1) and carrying out mass spectrometry on the sample containing the compound of formula (1). Also provided are methods of diagnosing whether a subject has a disease characterized by elastic fiber injury, a method for improving the accuracy and precision of mass spectroscopy analysis of a marker of elastic fiber injury, and kits for determining, by mass spectrometry, the amount of a marker of elastic fiber injury in a sample from a subject. Further provided are methods for preventing the progression of the effects associated with alpha-1 antitrypsin deficiency (AATD) in a subject with normal lung function.

Abstract: A process for preparing a compound represented by the following general formula (I) or a salt thereof, which comprises reacting lysine or a protective product thereof or a salt thereof with allysine or a protective product thereof in the presence of a specific trifluoromethane sulfonate to obtain a compound having pyridine ring or a salt thereof. (wherein, in the above-described general formula (I), one of R1 and R2 is —CH2CH2CH2CH(NH2)COOH group, and the other is hydrogen atom. And wherein, in the above-described general formula (I), one, or two or more of hydrogen atom, one, or two or more of carbon atom, or one, or two or more of nitrogen atom may be substituted with their isotope.