Page 15 - Read Online

Skoreński et al. Rare Dis Orphan Drugs J 2023;2:6 https://dx.doi.org/10.20517/rdodj.2022.21 Page 11 of 23

as a pair of donor and acceptor, ABZ-Tyr-Tyr-Abu-Asn-Glu-Pro-Tyr(3-NO )-NH with a K value of 3.2
2
2
M
-1 -1
3
[59]
mM and k /K value of 1596 × 10 M s , was reported one year later . A structure of simple chromogenic
M
cat
PR3 peptide substrates has also been developed, including Ac-Pro-Tyr-Asp-Ala-pNA and Ac-Asp-Tyr-Asp-
-1 -1
[60]
-1 -1
Ala-pNA, with a k /K value of 4201 ± 29.7 M s and 162 ± 12.8 M s respectively , as well as biotinylated
cat
M
derivative Bt-Val-Tyr-Asp-nVal-pNA with a k /K value of 80510 ± 2973 M s .
-1 -1[61]
cat
M
PR3 ABPs and Inhibitors
Azapro-3 (25), ABZ-Val-Ala-Asp-aza(nor)Val-Ala-Asp-Tyr-Gln-Tyr(3-NO ), is an example of the first
2
selective, non-covalent, reversible azapeptide inhibitor based on a structure of one of the FRET substrates
for PR3 [Figure 12]. This competitive inhibitor shows high activity and selectivity for PR3 with a K value of
i
1.5 µM, with a nonsignificant inhibitory effect of HNE, and without any reactivity towards other proteases,
including CatG, chymotrypsin, and granzyme B .
[58]
Another example of a PR3 inhibitor based on a sequence of its specific FRET substrate is ABZ-Val-Ala-Asp-
(nor) Val[Ψ](COCH )-Ala-Asp-Tyr-Gln-EDDnp (26), a ketomethylene peptide derivative [Figure 12]. This
2
compound was characterized as a competitive and reversible inhibitor with an IC value of 1.91 µM,
50
[62]
selective for PR3 over HNE .
Compound 6 (27), an analog of 2-aminobenzaldehyde oxime [Figure 13], was reported as the most potent
non-peptide inhibitor for PR3 from a synthesized set of compounds, with an IC value of 0.22 ± 0.02 µM.
50
However, this inhibitor showed a lack of selectivity due to better activity toward HNE
(IC = 0.05 ± 0.01 µM) .
[63]
50
Structures based on aminophosphonates constitute a well-known group of potent and selective PR3
[56]
inhibitors, which have been recently reviewed . The most important advantage of this class of inhibitors is
their lack of reactivity with other proteases, including threonine, cysteine, aspartyl, and metalloproteinases.
The first series of peptidyl derivatives α-aminoalkylphosphonate diaryl esters as specific, irreversible
inhibitors of PR3 was synthesized in 2014. This most potent covalent inhibitor, which acts as the transition
state analog, was Ac-Pro-Tyr-Asp-Ala (O-C H -4-Cl) (28) with the k /[I] value of 154 ± 3 M s . A
-1 -1
P
6
2
obs
4
P
biotinylated derivative of this compound, Bt-[PEG] -Pro-Tyr-Asp-Ala (O-C H -4-Cl) (29) was an example
66
6
,
2
4
of ABP, which can be used to visualize PR3 in native conditions, with k /[I] value of 1163 ± 0.1 M s
-1 -1
obs
[Figure 14]. However, this Bt-ABP lacked selectivity and showed activity toward HNE
(k /[I] = 46 ± 0.1 M s ) .
-1 -1 [60]
obs
Several peptidyl biotinylated derivatives of α-aminoalkylphosphonate dsiaryl esters with a potential of ABPs
F
f o r N S P s , i n c l u d i n g P R 3 w e r e d e s c r i b e d b y G r z y w a e t al. i v e o f t h e s e s t r u c t u r e s ,
Bt-Val-Pro-Abu (O-C H -4-S-CH ) , Bt-Val-Pro-Val (O-C H ) , Bt-Val-Pro-Val (O-C H -4-S-CH ) , Bt-
P
P
P
6
3 2
5 2
6
6
4
4
3 2
P
Val-Pro-Leu (O-C H -4-COOCH ) , Bt-LC-Suc-Phe-Val-Thr-(4Gu)Phg (O-C H -4-S-CH ) , show activity
P
6
3 2
4
6
3 2
4
toward PR3 with a k /[I] values of 5.1 × 10 ± 350, 1.6 × 10 ± 100, 1.6 × 10 ± 1,200, 1.9 × 10 ± 2,300,
4
4
3
3
obs
2.1 × 10 ± 100 [M s ], respectively. However, these ABPs do not show selectivity of action over HNE or
3
-1 -1
CatG [Table 1].
[64]
In 2018, the same research group reported a structure of a new biotinylated PR3 inhibitor, Bt-Val-Tyr-Asp-
-1 -1
nVal (O-C H -4-Cl) (30), with k /[I] value of 73,258 ± 5,342 M s , and without significant inhibitory
P
6
4
2
obs
activity toward HNE [Figure 14].
[61]