A Typical Protocol for Solid-Phase Synthesis

FIGURE 5.5 Schedule for the solid-phase synthesis of somatostatin, a 14-mer, on 10 g of resin reacted with 5 mequiv of the first amino acid, adapted from J. Rivier, J. Am. Chem. Soc. 96 2986, 1974. Min = time of mixing X2 = two times DCC = dicyclohexylcarbodiimide. Step 4 included 5% of (CH2SH)2 to prevent the oxidation of tryptophan. When the ninhydrin test on an aliquot after step 13 was negative, step 1 followed when positive, steps 9-13 were repeated. 

FIGURE 5.6 Reaction of ninhydrin (trioxohydrindene hydrate) with the amino group of a bound residue (A) generates the Schiff s base. Hydrolysis after shift of the double bond generates the aldehyde and another amine which reacts (B) with a second molecule of ninhydrin to give an equilibrium mixture of the anion depicted and its tetraoxo form with a maximum of absorbance at 570 nm. 

E Kaiser, RL Colescott, CD Bossinger, PI Cook. Color test for detection of free terminal amino groups in the solid-phase synthesis of peptides. Anal Biochem 34, 595, 1970. 

JEF Rivier. Somatostatin. Total solid phase synthesis. J Am Chem Soc 96, 2986, 1974. 

VK Sarin, SBH Kent, JP Tam, RB Merrifield. Quantitative monitoring of solid-phase peptide synthesis by the ninhydrin reaction. Anal Biochem 117, 147, 1981. 

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