Human psoriatic epidermis and scales were demonstrated to contain two antigenically separate cysteine proteinase inhibitors, one acidic with an isoelectric point of 4.7-5.0 (ACPI) and one neutral with an isoelectric point of 6.0-6.5 (NCPI), while normal epidermis contains only ACPI. The total papain (cysteine proteinase) inhibiting activity of the psoriatic epidermis as calculated per mg protein was higher than that in normal epidermis. Both ACPI and NCPI were localized immunocytochemically, mainly in the highest spinous cell layers with less activity in the parakeratotic cells and lower layers of spinous cells. Basal cells were essentially negative.

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Monocytes were separated from human peripheral blood and allowed to attach to culture flasks, after which the content and production of a number of cysteine proteinase inhibitors was assayed. These were: a low molecular weight (MW 12000) acid cysteine proteinase inhibitor (ACPI); a low-molecular weight inhibitor of the same size with neutral pH (NCPI), and alpha-cysteine proteinase inhibitor with a molecular weight around 90 000 (alpha-CPI). Only NCPI was detectable in the cultures at the beginning of the incubation, and it was synthesized and released into the incubation mixture during the incubation, especially if the cells were stimulated with silica. The amount of NCPI contained in and released from the cells was drastically decreased by puromycin. Immunoblots after cell electrophoresis in polyacrylamide gel revealed only one molecular form of NCPI with a molecular weight of 12 000 both in the cells and in the culture medium. No ACPI or alpha-CPI could be detected.

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Formamidase (EC 3.5.1.9) was purified from the soluble fraction of guinea pig liver by a procedure consisting of precipitation with ammonium sulphate, gel filtration on Sephadex G-100, salt precipitation, desalting with Sephadex G-25 and chromatography on calcium brushite and DEAE-cellulose. The specific activity was increased about 300-fold over that found in the initial homogenate. The purified enzyme protein had a molecular weight of 46000 as determined by gel filtration. The enzyme was readily inactivated during storage but could be stabilized by EDTA. It splits the amide bonds of Zusammenfassung: Formamidase in Meerschweinchenleber, L Reinigung und Charakterisierung. Formamidase (EC 3.5.1.9) wurde aus dem löslichen Überstand von Meerschweinchenleber etwa 300fach angereichert. Die Reinigungsschritte bestanden aus Ammoniumsulfatfällung, Gelfiltration an Sephadex G-100, erneuter Ammoniumsulfatfällung, Entsalzung an Sephadex G-25 und Chromatographie an Calciumhydrogenphosphat sowie an DEAE-Cellulose. Das durch Gelfiltration ermittelte Molekulargewicht des gereinigten Enzyms betrug 46000. Das Enzym verlor beim Lagern schnell an Aktivität, konnte aber durch EDTA stabilisiert werden. Es Formamidase (Aryl-formylamine amidohydrolase EC 3.5.1.9, formerly named kynurenine formamidase) is an enzyme active in the metabolism of tryptophan, liberating formic acid from ^-formyl-Lkynurenine, which is formed from tryptophan by tryptophan oxygenase (EC 1.13.1.12). MEHLER and KNOX demonstrated that formamidase of rat liver is also capable of catalysing the hydrolysis of for-W-formyl, N-acetyl and W-propionyl groups from substituted kynurenine, aniline, naphthylamine and aminofluorene. Monohalogen substituted acetyl groups were hydrolyzed even faster than formyl groups, but the amino acyl groups from the same substituted aromatic amines were not hydrolysed at all. Some aromatic but not liphatic estaers were also hydrolysed. The enzyme was optimally active at pH 6.8-6.9. It was readily inhibited by organic phosphorus compounds, but was not effected by EDTA or heavy metal ions, sulfhydryl groups or reagents etc. at concentrations lower than 10~4M. spaltet C/V-ständige) Formyl-, Acetyl-und Propionylgruppen von entsprechend substituiertem Kynurenin, Anilin, Naphthylamin und Aminofluoren ab. Monohalogen-substituierte Acetylgruppen werden noch schneller hydrolysiert als Formylgruppen, aber die Aminoacylgruppen desselben substituierten aromatischen Amins wurden überhaupt nicht angegriffen. Das Enzym hatte ein pH-Optimum bei pH 6,8-6,9, wurde durch Organophosphor-Verbindungen gehemmt, aber durch EDTA, Schwermetallionen, Sulfhydrylgruppen oder -reagenzien usw. in Konzentrationen kleiner als 10~4M nicht beeinflußt. myl derivatives of benzene 1 . The same is true in formamidase of Neurospora 2 .