The invention relates to a method for preparing peptides comprising the step of forming a peptide bond wherein the carboxyl group of a first amino acid or first peptide is activated and an amino group of the first activated amino acid or first peptide is protected by a protecting group having a water-solubility enhancing group and the activated carboxyl group of the first amino acid or first peptide is reacted with an amino group of a second amino acid or second peptide wherein said carboxyl group of the first amino acid or first peptide is activated in the absence of the second amino acid or second peptide. The invention further relates to peptides comprising a protecting group having a water-solubility enhancing group being bound to the amino group and an activated or free carboxyl group.

A peptide having a fluoroalkyl group as its side chain and a method for producing, which comprises condensing a compound represented by the formula (6-2) or (6-4), where means that an asymmetric carbon atom has an absolute configuration of S or R, Rf is a C.sub.1-30 alkyl group which is substituted with at least two fluorine atoms, and which may further be substituted with a halogen atom other than a fluorine atom (when the C.sub.1-30 alkyl group is a C.sub.2-30 alkyl group, it may have 1 to 5 etheric oxygen atoms between carbon atoms), and R.sup.2 is a protecting group for the amino group, with a fluorinated amino acid having its carboxy group protected, an amino acid having its carboxy group protected, a fluorinated peptide having its C-terminal protected, or a peptide having its C-terminal protected.

A peptide having a fluoroalkyl group as its side chain and a method for producing, which comprises condensing a compound represented by the formula (6-2) or (6-4), where means that an asymmetric carbon atom has an absolute configuration of S or R, Rf is a C.sub.1-30 alkyl group which is substituted with at least two fluorine atoms, and which may further be substituted with a halogen atom other than a fluorine atom (when the C.sub.1-30 alkyl group is a C.sub.2-30 alkyl group, it may have 1 to 5 etheric oxygen atoms between carbon atoms), and R.sup.2 is a protecting group for the amino group, with a fluorinated amino acid having its carboxy group protected, an amino acid having its carboxy group protected, a fluorinated peptide having its C-terminal protected, or a peptide having its C-terminal protected.

A method for increasing peptide fragmentation by labelling the peptide at the C-terminal end with a guanidinium group or other basic functional group and distinguishing isobaric amino acids and amino acid combinations of asparagine and glycine-glycine; glutamine and glycine-alanine; and/or glutamine and alanine-glycine, during polypeptide sequencing. The method involves: obtaining a peptide of interest and/or digesting a polypeptide of interest with a protease, such as pepsin, chymotrypsin or trypsin, or by chemical cleavage to produce shorter peptides; reacting the obtained and/or generated peptides with a coupling reagent to derivatize the free C-terminal carboxylic acid function of the peptides, thus adding a basic functional group rendering C-terminal peptide fragment ions detectable by mass spectrometry; selecting a charge state of 2+ or more, and fragmenting the derivatized peptides in a mass spectrometer under conditions effective to generate at least w ions; and detecting the w ions by mass spectrometry, and identifying derivatized peptides which incorporate the additional mass of the basic functional group.

A method for increasing peptide fragmentation by labelling the peptide at the C-terminal end with a guanidinium group or other basic functional group and distinguishing isobaric amino acids and amino acid combinations of asparagine and glycine-glycine; glutamine and glycine-alanine; and/or glutamine and alanine-glycine, during polypeptide sequencing. The method involves: obtaining a peptide of interest and/or digesting a polypeptide of interest with a protease, such as pepsin, chymotrypsin or trypsin, or by chemical cleavage to produce shorter peptides; reacting the obtained and/or generated peptides with a coupling reagent to derivatize the free C-terminal carboxylic acid function of the peptides, thus adding a basic functional group rendering C-terminal peptide fragment ions detectable by mass spectrometry; selecting a charge state of 2+ or more, and fragmenting the derivatized peptides in a mass spectrometer under conditions effective to generate at least w ions; and detecting the w ions by mass spectrometry, and identifying derivatized peptides which incorporate the additional mass of the basic functional group.

The present invention pertains to an improved chemical synthesis method for Ahp-cyclodepsipeptides which allows straight forward and easy synthesis of tailor-made Ahp-cyclodepsipeptides. The invention further provides Ahp-cyclodepsipeptides for use as HTRA protease inhibitors and their medical use.

The present invention pertains to an improved chemical synthesis method for Ahp-cyclodepsipeptides which allows straight forward and easy synthesis of tailor-made Ahp-cyclodepsipeptides. The invention further provides Ahp-cyclodepsipeptides for use as HTRA protease inhibitors and their medical use.

It was found that the use of an additive in a small amount relative to an amino acid or a peptide added to the N-terminus enables efficient progress of a condensation reaction even when an amino acid having large steric hindrance is contained, and the intended peptide compound can be obtained in a high yield and with a high purity.

It was found that the use of an additive in a small amount relative to an amino acid or a peptide added to the N-terminus enables efficient progress of a condensation reaction even when an amino acid having large steric hindrance is contained, and the intended peptide compound can be obtained in a high yield and with a high purity.

Selectively controllable cleavable linkers include electrochemically-cleavable linkers, photolabile linkers, thermolabile linkers, chemically-labile linkers, and enzymatically-cleavable linkers. Selective cleavage of individual linkers may be controlled by changing local conditions. Local conditions may be changed by activating electrodes in proximity to the linkers, exposing the linkers to light, heating the linkers, or applying chemicals. Selective cleaving of enzymatically-cleavable linkers may be controlled by designing the sequences of different sets of the individual linkers to respond to different enzymes. Cleavable linkers may be used to attach polymers to a solid substrate. Selective cleavage of the linkers enables release of specific polymers from the solid substrate. Cleavable linkers may also be used to attach protecting groups to the ends of growing polymers. The protecting groups may be selectively removed by cleavage of the linkers to enable growth of specific polymers.