Z-DNA, n.

z-dna
http://www.oed.com/dictionary/z-dna_n%3Ftab%3Dmeaning_and_use
First published 1986; not fully revised

# Z-DNAnoun

## Factsheet

### What does the noun Z-DNA mean?

There is one meaning in OED's entry for the noun Z-DNA. See ‘Meaning & use’ for definition, usage, and quotation evidence.

#### Entry status

OED is undergoing a continuous programme of revision to modernize and improve definitions. This entry has not yet been fully revised.

### How common is the noun Z-DNA?

About 0.04occurrences per million words in modern written English

2017 | 0
2018 | 0.0015
2019 | 0.0023
2020 | 0.0047
2021 | 0.0053
2022 | 0.0079
2023 | 0.0083
2024 | 0.0093

### Where does the noun Z-DNA come from?

Earliest known use

1970s

The earliest known use of the noun Z-DNA is in the 1970s.

OED's earliest evidence for Z-DNA is from 1979, in a text by A. H.-J. Wang et al.

### Nearby entries

1. zawn, n. 1865–
2. zayat, n. 1823–
3. zayde, n. 1946–
4. zazen, n. 1727–
5. zazzy, adj. 1961–
6. Z band, n. 1950–
7. ZBB, n. 1976–
8. Z-bed, n. 1973–
9. Z-car, n. 1961–
10. Z-day, n. 1925–
11. Z-DNA, n.1979–
12. ze, pron. 1864–
13. zea, n. 1562–
14. zeagonite, n. 1823–
15. zeal, n. a1382–
16. zeal, v. 1542–1687
17. Zealander, n.¹ 1663–
18. Zealander, n.² 1773–
19. Zealandic, adj. 1807–
20. Zealandish, adj. 1684–
21. zealator, n. a1464–

## Meaning & use

Biochemistry.

1. 1979–
   DNA in which the double helix has a left-handed rather than the usual right-handed twist and the sugar phosphate backbone follows a zigzagged course.
   1. 1979

      > In looking at this left-handed helix..it is apparent that the ribose-phosphate backbone follows a zig-zag course resulting from alternating residue conformations. Accordingly, we propose to call this Z-DNA.

      A. H.-J. Wang et al. in Nature 13 December 681/2
   2. 1983

      > In Z DNA..the repeating unit of the helix is not a single base pair, as it is in A and B DNA, but rather two successive base pairs: G–C followed by C–G.

      Scientific American December 92/1
   genetics organic chemistry
   1. thymo-nucleic acid 1904–
      Of or pertaining to the nuclein of the thymus gland; in thymo-nucleic acid, either of two or more nucleic acids, which can be isolated from the…
   2. deoxyribonucleic acid 1931–
      A generic term for any of the nucleic acids which yield deoxyribose on hydrolysis, which are generally found in and confined to the chromosomes of…
   3. DNA 1944–
      = deoxyribonucleic acid, n. Cf. RNA, n.
   4. DNase 1949–
      = deoxyribonucleic acid, n. Cf. RNase, n.
   5. C 1958–
      Biochemistry. Designating a form of double-stranded DNA adopted in the presence of certain solvents, consisting of a right-handed double helix…
   6. minicircle 1967–
      Any small circular DNA molecule; esp. any of those present in large numbers in the kinetoplasts of trypanosomatids, which code for guide RNAs that…
   7. Z-DNA 1979–
      DNA in which the double helix has a left-handed rather than the usual right-handed twist and the sugar phosphate backbone follows a zigzagged course.
   View in Historical Thesaurus

## Frequency

Z-DNA typically occurs about 0.04 times per million words in modern written English.

Z-DNA is in frequency band 3, which contains words occurring between 0.01 and 0.1 times per million words in modern written English. More about OED's frequency bands

Frequency data is computed programmatically, and should be regarded as an estimate.

### Frequency of Z-DNA, n., 1970–2010

* Occurrences per million words in written English

Historical frequency series are derived from Google Books Ngrams (version 2), a data set based on the Google Books corpus of several million books printed in English between 1500 and 2010.

The overall frequency for a given word is calculated by summing frequencies for the main form of the word, any plural or inflected forms, and any major spelling variations.

For sets of homographs (distinct entries that share the same word-form, e.g. mole, n.¹, mole, n.², mole, n.³, etc.), we have estimated the frequency of each homograph entry as a fraction of the total Ngrams frequency for the word-form. This may result in inaccuracies.

Smoothing has been applied to series for lower-frequency words, using a moving-average algorithm. This reduces short-term fluctuations, which may be produced by variability in the content of the Google Books corpus.

Decade | Frequency per million words
--- | ---
1970 | 0.038
1980 | 0.036
1990 | 0.036
2000 | 0.036
2010 | 0.045

### Frequency of Z-DNA, n., 2017–2024

* Occurrences per million words in written English

Modern frequency series are derived from a corpus of 20 billion words, covering the period from 2017 to the present. The corpus is mainly compiled from online news sources, and covers all major varieties of World English.

Smoothing has been applied to series for lower-frequency words, using a moving-average algorithm. This reduces short-term fluctuations, which may be produced by variability in the content of the corpus.

Period | Frequency per million words
--- | ---
2017 | 0
2018 | 0.0015
2019 | 0.0023
2020 | 0.0047
2021 | 0.0053
2022 | 0.0079
2023 | 0.0083
2024 | 0.0093

Originally published as part of the entry for Z, n.

Z, n. was first published in 1921; not fully revised.