Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing.
BACKGROUND: Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of an extensive kallikrein family of proteases. Both proteases are secreted as zymogens or proenzymes containing a seven amino acid propeptide that must be proteolytically removed for enzymatic activation....
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
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2001
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| _version_ | 1797066913597095936 |
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| author | Denmeade, SR Lövgren, J Khan, SR Lilja, H Isaacs, J |
| author_facet | Denmeade, SR Lövgren, J Khan, SR Lilja, H Isaacs, J |
| author_sort | Denmeade, SR |
| collection | OXFORD |
| description | BACKGROUND: Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of an extensive kallikrein family of proteases. Both proteases are secreted as zymogens or proenzymes containing a seven amino acid propeptide that must be proteolytically removed for enzymatic activation. The physiological proteases that activate pro-hK2 and pro-PSA are not known. METHODS: The pro-hK2 peptide sequence is Val-Pro-Leu-Ile-Gln-Ser-Arg (VPLIQSR). For PSA, the amino acid sequence of the propeptide is Ala-Pro-Leu-Ile-Leu-Ser-Arg (APLILSR). Fluorescent substrates were made by coupling these peptide sequences to 7-amino-4-methylcoumarin (AMC). The hydrolysis of the VPLIQSR-AMC and APLILSR-AMC substrates by hK2, PSA, and a panel of purified proteases was determined. RESULTS: HK2 readily cleaved the pro-hK2 peptide substrate VPLIQSR-AMC with a rate of hydrolysis that was approximately 8-fold higher than an equimolar amount of purified trypsin. HK2 also had the highest hydrolysis rate from among a group of other trypsin-like proteases. In contrast, neither hK2 nor PSA was able to appreciably cleave the pro-PSA substrate APLILSR-AMC. The pro-PSA substrate was most readily hydrolyzed by urokinase and trypsin. CONCLUSIONS: HK2 can hydrolyze the pro-hK2 substrate suggesting that maturation of pro-hK2 to enzymatically active hK2 involves autoprocessing. As expected, PSA, a chymotrypsin-like protease, was unable to hydrolyze either of the propeptide substrates. Therefore, it is unlikely that PSA can auto-process its own enzymatic function. HK2 has trypsin-like specificity but was unable to hydrolyze the pro-PSA substrate. These results raise the possibility that an additional processing protease may be required to fully process PSA to an enzymatically active form. |
| first_indexed | 2024-03-06T21:48:49Z |
| format | Journal article |
| id | oxford-uuid:4a8ad6ae-ae7b-412d-9659-25f878eec58d |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T21:48:49Z |
| publishDate | 2001 |
| record_format | dspace |
| spelling | oxford-uuid:4a8ad6ae-ae7b-412d-9659-25f878eec58d2022-03-26T15:38:08ZActivation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:4a8ad6ae-ae7b-412d-9659-25f878eec58dEnglishSymplectic Elements at Oxford2001Denmeade, SRLövgren, JKhan, SRLilja, HIsaacs, JBACKGROUND: Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of an extensive kallikrein family of proteases. Both proteases are secreted as zymogens or proenzymes containing a seven amino acid propeptide that must be proteolytically removed for enzymatic activation. The physiological proteases that activate pro-hK2 and pro-PSA are not known. METHODS: The pro-hK2 peptide sequence is Val-Pro-Leu-Ile-Gln-Ser-Arg (VPLIQSR). For PSA, the amino acid sequence of the propeptide is Ala-Pro-Leu-Ile-Leu-Ser-Arg (APLILSR). Fluorescent substrates were made by coupling these peptide sequences to 7-amino-4-methylcoumarin (AMC). The hydrolysis of the VPLIQSR-AMC and APLILSR-AMC substrates by hK2, PSA, and a panel of purified proteases was determined. RESULTS: HK2 readily cleaved the pro-hK2 peptide substrate VPLIQSR-AMC with a rate of hydrolysis that was approximately 8-fold higher than an equimolar amount of purified trypsin. HK2 also had the highest hydrolysis rate from among a group of other trypsin-like proteases. In contrast, neither hK2 nor PSA was able to appreciably cleave the pro-PSA substrate APLILSR-AMC. The pro-PSA substrate was most readily hydrolyzed by urokinase and trypsin. CONCLUSIONS: HK2 can hydrolyze the pro-hK2 substrate suggesting that maturation of pro-hK2 to enzymatically active hK2 involves autoprocessing. As expected, PSA, a chymotrypsin-like protease, was unable to hydrolyze either of the propeptide substrates. Therefore, it is unlikely that PSA can auto-process its own enzymatic function. HK2 has trypsin-like specificity but was unable to hydrolyze the pro-PSA substrate. These results raise the possibility that an additional processing protease may be required to fully process PSA to an enzymatically active form. |
| spellingShingle | Denmeade, SR Lövgren, J Khan, SR Lilja, H Isaacs, J Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing. |
| title | Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing. |
| title_full | Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing. |
| title_fullStr | Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing. |
| title_full_unstemmed | Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing. |
| title_short | Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing. |
| title_sort | activation of latent protease function of pro hk2 but not pro psa involves autoprocessing |
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