FCETAL NUTRITION: THE PLACENTA 507 



ferments 



Various enzymes have Ireen investigated in the placenta. They 

 may be grouped according to the chemical nature of the actions 

 which they produce, as follows : (1) Hydrolytic reactions, (2) oxida- 

 tion reactions, (3) removal of amino groups from amino-acids, and 

 (4) decomposition of peroxides. 



(1) A proteolytic enzyme was found by Ascoli, 1 and subsequently 

 by Merletti,' 2 Bergell and Liepmann, 3 Savare, 4 and others. Bottazzi 5 

 states that placental tissue can transform glycogen into maltose, and 

 a similar action is strongly produced by glycerine extracts of the 

 maternal and fatal placenta of the rabbit (see p. 462). 



Savare holds that the transformation of glycogen to sugar is due 

 to the blood; but the fact that extracts of the Ungulate placenta', 

 which also contain blood, do not possess the same power, forces us to 

 conclude that the enzyme activity in the rabbit and man depends on 

 the placental tissue. No lipolytic enzyme is present in the placenta 

 (Charrin and Goupil c ). 



(2) The oxidation of aromatic aldehydes by the placenta has been 

 obtained by Hofbauer and by Ferroni, 7 not by Savare or Charrin and 

 Goupil. V. Fiirth and Schneider 8 state that tyrosine is oxidised 1 v 

 contact with the placenta, resulting in the production of a dark 

 pigment, and they have suggested that tin's reaction may be related 

 to the special pigmentation of pregnancy. 



(3) Savare states that the placenta transforms the NH 2 group of 

 amino-acids into ammonia by means of a special ferment, a desamidase. 



(4) Decomposition of peroxides may be produced by enzymes, the 

 so-called indirect oxidases, and is sometimes regarded as the means 

 ly which oxidation changes are restricted to the appropriate parts of 

 the body, and secluded, for instance, from the blood (Leathes 9 ). The 

 guaiacol reaction, by which a colourless solution of guaiacol becomes 

 red, takes place, according to Charrin and Goupil, when hydrogen 

 peroxide is present ; in other words, placental tissue decomposes the 

 peroxide, and the nascent oxygen oxidises guaiacol. Hofbauer, 



1 Ascoli, "Passiert Eiweiss die placentare Scheidewand .'" Z<ifg'-/i. /. i>f<ys, 

 Chemie, vol. xxxvi., 1902. 



- Merletti, " Ricerche e studi intorno ai poteri selettivi del' epitelio dei villi 

 coriali," /.'".. <ru.it. . Gfinec,, 1903. 



3 Bergell and Liepmann, " Ueber die in der Placenta enthaltenen Fennente," 

 M''i i-l,. ,,<"<L \\'ch., 1905. 



* Savare, " Zur Kenntnis der Fermente der Placenta," Hofmeitter's Beitnfge, 

 vol. ix., 1907. 



5 Bottazzi, "Placental Activity," Roll. <l>'ll<i I!. .!<-,>,/. ,</. ////,//?, vol. xviii. 

 u Charrin et Goupil, "Physiologic du Placenta,' t'nt/>t. li- ml. <!< /M<W. cfes 

 X. /. //'".*, vol. cxli., 1905 ; also vol. cxlii., 1906. 



~ Ferroni, "L'eterolisi utero-placentare, .I/'/-. <li u.it. '///<., 1905. 



8 V. Fiirth and Schneider, " Ueber tierische Tyrosinasen und ihre 

 Beziehungen zur Pigmentbildung," Hi>fin>-i*t'-i-'* />< ///v/v/c, vol. i. 



9 Leathes, I'l-ohlom* in Animaf M<>t'tl>H.<in. Ijondon, 1907. 



