Peptide Hormones and their Prohormones as Biomarkers

Figures & data

Figure 1. Principle in processing-independent analysis.

Plasma is incubated with an endoprotease in order to produce a small peptide fragment. The fragment is then measured by standard immunoassays.

Table 1. Post-translational modifications.

Endoproteolytic cleavages	Exoproteolytic trimmings	Amino acid derivatizations
Dibasic sites	Carboxyamidation	Acylation
Monobasic sites	Glutaminyl cyclation	Disulfide bridging
Post-(poly) Glu/Asp sites	N-terminal dipeptidyl cleavage	γ-carboxylation
Post-Phe-sites		Glycosylation
Tri- and tetrabasic sites		Isomerization Phosphorylation Sulfation Octanoylation

Table 2. Cholecystokinin concentrations in normal human plasma.

Assay epitope	Plasma concentrations (pmol/l)		Year of publication
	Basal	Maximal
Unknown	<960	77,000	1969
Unknown	7	2000	1973
N-terminus of CCK-33	1220	2330	1973
N-terminus of CCK-33	186	293	1975
Unknown	97	123	1977
Unknown	2400	4300	1978
C-terminus of CCK-33	8	24	1981
C-terminus of CCK-33	27	51	1982
Subtraction assay	<0.8	2	1982
Subtraction assay	<0.2	1	1982
C-terminus of CCK-33	11	25	1982
C-terminus of CCK-33	<6	30	1982
Unknown	5	12	1983
C-terminus of CCK-33	3	9	1983
Midregion of CCK-33	3	10	1983
C-terminus of CCK-33	16	28	1983
C-terminus of CCK-33	15	22	1984
C-terminus of CCK-33	6	23	1984
C-terminus of CCK-33	3	10	1985
C-terminus of CCK-33	1	7	1985
Subtraction assay	14	–	1985
C-terminus of CCK-33	2	7	1986
C-terminus of CCK-33	2	27	1987
CCK-8	11	41	1988
CCK-8	1	3	1991
C-terminus of CCK-33	2	7	1992
C-terminus of CCK-33	1	5	1992
C-terminus of CCK-33	1	4	1993
CCK-8	0.5	–	1995
N-terminus of CCK-22	1	2	1995
C-terminus of CCK-12	1	5	1998

CCK: Cholecystokinin.

Data taken from [16].

Rehfeld JF : How to measure cholecystokinin in tissue, plasma and cerebrospinal fluid.Regul. Pept.78(1–3), 31–39 (1998).

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