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物。在俄亥俄州立大學的一項研究中 [3],科學家發現生吃含豐富多酚                           " )JTUPSZ PG 1MBTNJET
 (polyphenols)的食物可以減少進食蒜頭後呼吸中 AMS 的含量。
 在某程度上中和它們的氣味。然而,多酚氧化酶可將多酚氧化為更有                   From Discovery to
 硫醇(allyl mercaptan)的臭味化合物,防止其進一步被人體代謝成                                   Application
 難以分解的「親戚」AMS [3]。蘋果、布冧、車厘子、桃和葡萄等富含
 多酚的常見水果均在研究中被發視具有除臭作用 [4, 5],當中蘋果更
 在實驗中被證實能降低 AMS 水平 [3]。像大多數酶一樣,多酚氧化酶                   ሯ୐ٙዝ̦j㉿䥝䛟┑㒪䠉

 即使你不喜歡水果也不用擔心,其他研究表明,喝牛奶亦能有效                                                              By Henry Lau 劉以軒
 對付蒜頭味口氣 [6]。揮發性硫化物的化學結構可分為親水性和疏水
 性(即親脂性);研究發現在飲用牛奶後,這些化合物(包括 AMS)在      The  wor ld  of  life   lab was nothing short of spectacular, combining not
 口腔和鼻腔內的濃度都分別降低。由於牛奶主要由水和數個百分比的  sci e n ce  i s  a b uz z  w it h   one but three important stories.
 脂肪組成,它可以同時溶解親水性和疏水性的有機硫化物,從而降低  exciting  news  all  the  time.
 其揮發性。此外,酪蛋白(casein),一種牛奶中的蛋白質,亦被證明  Over the years, there have been   The first part of the trilogy began near the mid-
 能與二烯丙基二硫(diallyl disulfide)等的二硫化物發生化學反應。  golden rice and glowing mice, CRISPR   20th century. First glimpsed in the 1940s, plasmids
 據推測,二烯丙基二硫可以在還原途徑(reductive pathway)中與  and many more head-turning projects. It   were stumbled upon by scientists who wished to
                                                              discover why some traits could be passed on by non-
 麩胱甘肽(glutathione)被代謝成 AMS;當中麩胱甘肽是溫和的還  may surprise you that these curious biological   chromosomal DNA structures [1]. In the beginning,
 原劑,能被我們的細胞用來還原二硫鍵 [7]。牛奶中的脂肪和酪蛋白  wonders around the world owe their success to a   various scientists gave these circular DNA entities
 可以減少體內可用的親脂分子二烯丙基二硫,從而減少 AMS 的形成。  teeny-tiny thing known as a plasmid.  different names such as “pangene” or “cytogene”.
 這些就是為何喝牛奶可以減少蒜頭味口氣的原因。  One might say that modern biological research   It wasn’t until 1952 that Lederberg coined the term

        relies heavily on DNA technology. Ever since the      “plasmid”  [1],  which  has  been  used  ever  since.
 防止蒜頭味口氣,更可以使營養變得更豐富!  confirmation of DNA as the “blueprint” of life and its   He defined it as a “hereditary extrachromosomal
        characteristics were elucidated by many scientists    element”. In simpler words, plasmids exist outside of
        over the years, DNA has become an integral part of    the host’s chromosome and can replicate themselves
 1 編按:第十五期《科言》內有更多關於屁的科學知識。
        life science research. Nowadays, scientists introduce   independently  of  the  host  genome.  Despite  its
        foreign DNA as an extra set of commands into cell, to   independence, upon cell division, plasmids can also
        achieve all kinds of effects. The tool that has enabled   be passed from parent cells to daughter cells, that’s
        all these is known as a plasmid. Next to the colossal   why it’s called a “hereditary” element. That being said,
        coiled beast that is the bacterial chromosome, a      plasmids are not always retained and can be lost after
 References  參考資料:  plasmid is but an inconspicuous dot. It is a small   a certain number of cell divisions.
 [1] Suarez F, Springfield J, Furne J, Levitt M. Differentiation  stretch of DNA that serves as a vector. Think of it as
 of mouth versus gut as site of origin of odoriferous            Soon after the coining of the term “plasmid”,
 breath gases after garlic ingestion. Am J Physiol.  an inbound car that takes the passenger, namely
 1999;276(2):G425-G430. doi:10.1152/ajpgi.1999.276.2.G425  the foreign DNA, into another cell, by crossing the   scientists were able to determine that plasmids
 [2] Taucher J, Hansel A, Jordan A, Lindinger W. Analysis of  cell’s borders, namely the cell membrane, so that the   could provide special abilities to their hosts, much
 Compounds in Human Breath after Ingestion of Garlic          like modular upgrades that allowed bacteria to
 Using Proton-Transfer-Reaction Mass Spectrometry. J. Agric.  foreign DNA can perform its function inside the cell.
 Food Chem. 1996;44(12):3778-3782. doi:10.1021/jf960640e  While often overlooked, the plasmid’s journey into the   survive better in extreme circumstances, although
 [3] Munch R, Barringer SA. Deodorization of Garlic Breath
 Volatiles by Food and Food Components. J Food Sci.
 2014;79(4):C526-C533. doi:10.1111/1750-3841.12394
 [4] Negishi O, Negishi Y. Enzymatic Deodorization with Raw
 Fruits, Vegetables and Mushrooms. Food Sci. Technol. Res.
 [5] Negishi O, Negishi Y, Ozawa T. Effects of food materials
 on removal of Allium-specific volatile sulfur compounds.
 J Agric Food Chem. 2002;50(13):3856-3861. doi:10.1021/
 [6] Hansanugrum A, Barringer SA. Effect of milk on the
 deodorization of malodorous breath after garlic ingestion.
 J Food Sci. 2010;75(6):C549-C558. doi:10.1111/j.1750-
 [7] Rosen RT, Hiserodt RD, Fukuda EK, et al. The
 determination of metabolites of garlic preparations
 in breath and human plasma. Biofactors. 2000;13
 (1-4):241-249. doi:10.1002/biof.5520130137
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